April / May 2021   |   Volume 19   |   Issue 3

Common Complications of Tibial Plateau-Leveling Osteotomy

in this issue

in this issue

Common Tibial Plateau-Leveling Osteotomy Complications

Feline Orthopedic Examination

Leptospirosis

Differential Diagnosis: Proteinuria in Dogs

Differential Diagnosis: Proteinuria in Cats

Sudden Onset of Fear & Panic in a Bernese Mountain Dog

Rough Anesthetic Recoveries

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Nexgard CB AprilMay 2021

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Ellevet CB AprilMay 2021

Differential Diagnosis: Proteinuria in Cats

Barry Hedgespeth, BVSc, North Carolina State University

Karyn Harrell, DVM, DACVIM, North Carolina State University

Urology & Nephrology

|Peer Reviewed

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Differential Diagnosis: Proteinuria in Cats

Following are differential diagnoses for cats presented with proteinuria.

Prerenal

  • Hemoglobinuria
  • Myoglobinuria 
  • Light chain immunoglobulins (multiple myeloma, lymphoma)

Renal

  • Functional or physiologic
    • Congestive heart failure
    • Strenuous exercise
    • Fever
    • Seizure
    • Exposure to extreme temperatures
  • Glomerular
    • Infectious
      • Bacterial (eg, chronic bacterial infection, mycoplasmal polyarthritis, endocarditis)
      • Viral (eg, FIV, feline infectious peritonitis, FeLV)
      • Protozoal (eg, toxoplasmosis) 
      • Fungal (eg, cryptococcosis, other systemic fungal infection)
    • Inflammatory
      • Acute pancreatitis
      • Cholangiohepatitis
      • Chronic progressive polyarthritis
      • Systemic lupus erythematosus
      • Other immune-mediated diseases
    • Neoplastic
      • Leukemia
      • Lymphoma
      • Mastocytosis
    • Miscellaneous
      • Acromegaly
      • Drug reactions
      • Diabetes mellitus
      • Corticosteroids (endogenous/spontaneous hyperadrenocorticism and exogenous)
      • Hyperthyroidism
      • Systemic hypertension
    • Familial
      • Membranous nephropathy
      • Amyloidosis (Abyssinian, Siamese)
  • Tubulointerstitial
    • Chronic kidney disease
    • Acute kidney injury
      • Toxins (eg, NSAIDs, acetaminophen, ethylene glycol, lilies [Lilium and Hemerocallis spp], heavy metal ingestion [eg, lead, mercury, arsenic, thallium], insect or snake bite)
      • Hypotension

Postrenal

  • Bacterial cystitis
  • Idiopathic cystitis/FLUTD
  • Urolithiasis
  • Neoplasia (eg, urothelial carcinoma, other)
  • Prostatitis (rare in cats)
  • Vaginitis
  • Pyometra

References

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Digital Edition may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.


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Common Tibial Plateau-Leveling Osteotomy Complications

Dominique Hemmings, DVM, Tuskegee University

Selena Tinga, DVM, PhD, DACVS-SA, The Ohio State University

Orthopedics

|Peer Reviewed

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Common Tibial Plateau-Leveling Osteotomy Complications

The cranial cruciate ligament (CrCL) resists cranial tibial translation, internal tibial rotation, and stifle hyperextension.1 Rupture of the CrCL (CrCLR) is the most common cause of hindlimb lameness in dogs,1 often resulting in instability, meniscal tearing, and osteoarthritis. CrCL degeneration is caused by a combination of factors, including age, obesity, trauma, genetics, and abnormal bony morphology.1

Complete CrCLR can typically be diagnosed via palpation (positive cranial drawer or tibial thrust), although early or partial tears are more challenging to diagnose.1 Radiography should be performed to identify findings supportive of CrCLR (eg, stifle joint effusion, osteoarthritis, cranial tibial subluxation), to rule out other causes of pain or instability (eg, fractures, neoplasia), and for surgical planning.1

Treatment options for CrCLR include osteotomy-based procedures, extracapsular suture procedures, and nonsurgical management. A survey suggested that surgeons prefer tibial plateau-leveling osteotomy (TPLO) for treatment of most cases of CrCLR in dogs weighing >33 lb (15 kg).2-7 Several studies report an equal to superior outcome for TPLO as compared with extracapsular suture procedures and other osteotomy procedures.3-7 For example, some studies have shown TPLO to have a quicker return to normal weight bearing, higher pet owner satisfaction, and slower progression of osteoarthritis.3-7 However, 10% to 34% of dogs treated with TPLO develop a complication, with up to 4% requiring revision surgery.7 Complications may arise from inappropriate candidate selection, imperfect surgical technique, or poor owner compliance, but complications are also an inherent risk of surgery in any patient.

Common TPLO Complications

Surgical Site Infection

The incidence of surgical site infection (SSI) after TPLO ranges from 1.3% to 25.6%, with a wide reported range secondary to variable definitions of SSI risk factors and methodology.8-12 SSI can occur in superficial and/or deep tissues and includes the subcategories of soft tissue infection, implant-associated infection, osteomyelitis, or septic arthritis. A large review reported the incidence of SSI subcategories occurring after TPLO by taking case numbers from numerous primary studies; wound complications occurred in 7.8% of TPLO cases, implant-associated infection occurred in 3.4%, osteomyelitis occurred in 0.6%, and septic arthritis occurred in 0.8%.6

Reported risk factors for development of post-TPLO SSI include German shepherd breed, heavier body weight, undergoing a meniscectomy, inexperienced surgeon, and prolonged duration of surgery and anesthesia.8-10 One study reported a nonsignificant trend toward increased SSI rate after TPLO in dogs with dermatitis8; thus, the authors recommend giving consideration to surgical delay and controlling dermatitis prior to elective orthopedic surgery, particularly when dermatitis is severe or within the surgical site. In addition to sterile technique, the risk for SSI is likely mitigated by meticulous tissue handling, accurate wound closure, minimizing the duration of surgery and anesthesia, copious lavage, and perioperative administration of a first-generation cephalosporin antibiotic (eg, cefazolin).8,9 One study documented a significant reduction in SSI rate from 8.5% to 1.3% after implementation of a strict infection control protocol that included use of an adhesive iodine-impregnated drape during surgery, single use gloves at all times when handling dogs, and an Elizabethan collar, in addition to multiple additional efforts.11

The use of perioperative antibiotics is supported, but there is conflicting evidence regarding the use of postoperative antibiotics, and the potential protective effects must be weighed against the risk for developing bacterial drug resistance.8-10 If an SSI occurs, immediate and aggressive wound management, bacterial culture, and antibiotic therapy are all recommended to control the infection while the bone heals. Even superficial soft tissue infections can progress to implant-associated infections and osteomyelitis, especially if not treated appropriately, and can result in delayed union, nonunion, or persistent infection (Figures 1 and 2).7 Treatment for an implant-associated infection, osteomyelitis, or septic arthritis requires long-term antibiotic therapy, possible surgical flush, debridement, and/or local antimicrobial therapies, as well as implant removal in many cases, once bone healing is confirmed.13

In rare cases, infection cannot be controlled, bone healing cannot be achieved, and amputation or euthanasia is required.

A 5-year-old neutered male Rottweiler that developed a deep surgical site infection 5 days after TPLO. Prior to removal of intradermal sutures (A), thick serosanguinous discharge was easily expelled from the incision in multiple locations (inset). After removal of intradermal sutures (B), the TPLO plate was immediately visible, indicating dehiscence of the fascial closure, and the tissues appeared inflamed and were coated with a thick mucoid film. The wound was managed as an open wound for 4 days then closed once tissues appeared healthy, and the implant was not removed; the patient remained on oral culture-based antibiotics until healing of the osteotomy (delayed union). This dog did not develop osteomyelitis and had no lameness at the last follow-up.
A 5-year-old neutered male Rottweiler that developed a deep surgical site infection 5 days after TPLO. Prior to removal of intradermal sutures (A), thick serosanguinous discharge was easily expelled from the incision in multiple locations (inset). After removal of intradermal sutures (B), the TPLO plate was immediately visible, indicating dehiscence of the fascial closure, and the tissues appeared inflamed and were coated with a thick mucoid film. The wound was managed as an open wound for 4 days then closed once tissues appeared healthy, and the implant was not removed; the patient remained on oral culture-based antibiotics until healing of the osteotomy (delayed union). This dog did not develop osteomyelitis and had no lameness at the last follow-up.

Figure 1 A 5-year-old neutered male Rottweiler that developed a deep surgical site infection 5 days after TPLO. Prior to removal of intradermal sutures (A), thick serosanguinous discharge was easily expelled from the incision in multiple locations (inset). After removal of intradermal sutures (B), the TPLO plate was immediately visible, indicating dehiscence of the fascial closure, and the tissues appeared inflamed and were coated with a thick mucoid film. The wound was managed as an open wound for 4 days then closed once tissues appeared healthy, and the implant was not removed; the patient remained on oral culture-based antibiotics until healing of the osteotomy (delayed union). This dog did not develop osteomyelitis and had no lameness at the last follow-up.

A 5-year-old neutered male Rottweiler that developed a deep surgical site infection 5 days after TPLO. Prior to removal of intradermal sutures (A), thick serosanguinous discharge was easily expelled from the incision in multiple locations (inset). After removal of intradermal sutures (B), the TPLO plate was immediately visible, indicating dehiscence of the fascial closure, and the tissues appeared inflamed and were coated with a thick mucoid film. The wound was managed as an open wound for 4 days then closed once tissues appeared healthy, and the implant was not removed; the patient remained on oral culture-based antibiotics until healing of the osteotomy (delayed union). This dog did not develop osteomyelitis and had no lameness at the last follow-up.
A 5-year-old neutered male Rottweiler that developed a deep surgical site infection 5 days after TPLO. Prior to removal of intradermal sutures (A), thick serosanguinous discharge was easily expelled from the incision in multiple locations (inset). After removal of intradermal sutures (B), the TPLO plate was immediately visible, indicating dehiscence of the fascial closure, and the tissues appeared inflamed and were coated with a thick mucoid film. The wound was managed as an open wound for 4 days then closed once tissues appeared healthy, and the implant was not removed; the patient remained on oral culture-based antibiotics until healing of the osteotomy (delayed union). This dog did not develop osteomyelitis and had no lameness at the last follow-up.

Figure 1 A 5-year-old neutered male Rottweiler that developed a deep surgical site infection 5 days after TPLO. Prior to removal of intradermal sutures (A), thick serosanguinous discharge was easily expelled from the incision in multiple locations (inset). After removal of intradermal sutures (B), the TPLO plate was immediately visible, indicating dehiscence of the fascial closure, and the tissues appeared inflamed and were coated with a thick mucoid film. The wound was managed as an open wound for 4 days then closed once tissues appeared healthy, and the implant was not removed; the patient remained on oral culture-based antibiotics until healing of the osteotomy (delayed union). This dog did not develop osteomyelitis and had no lameness at the last follow-up.

Figure 1 A 5-year-old neutered male Rottweiler that developed a deep surgical site infection 5 days after TPLO. Prior to removal of intradermal sutures (A), thick serosanguinous discharge was easily expelled from the incision in multiple locations (inset). After removal of intradermal sutures (B), the TPLO plate was immediately visible, indicating dehiscence of the fascial closure, and the tissues appeared inflamed and were coated with a thick mucoid film. The wound was managed as an open wound for 4 days then closed once tissues appeared healthy, and the implant was not removed; the patient remained on oral culture-based antibiotics until healing of the osteotomy (delayed union). This dog did not develop osteomyelitis and had no lameness at the last follow-up.

Radiographs from an 8-year-old spayed Rottweiler that underwent TPLO and was diagnosed with a superficial SSI 2 weeks postoperatively at another hospital. The SSI was treated with a 10-day course of antibiotics. The dog was presented to The Ohio State University Veterinary Hospital 6 weeks after surgery for recurrent lameness; the incision was healed, but osteomyelitis was confirmed on radiographs and fine-needle aspirate and cytology. Culture-based antibiotics were prescribed, but the infection did not resolve, the lameness was persistent, and the osteotomy became a nonunion. The patient was euthanized after developing a T3-L3 myelopathy suspected to be related to systemic infection.
Radiographs from an 8-year-old spayed Rottweiler that underwent TPLO and was diagnosed with a superficial SSI 2 weeks postoperatively at another hospital. The SSI was treated with a 10-day course of antibiotics. The dog was presented to The Ohio State University Veterinary Hospital 6 weeks after surgery for recurrent lameness; the incision was healed, but osteomyelitis was confirmed on radiographs and fine-needle aspirate and cytology. Culture-based antibiotics were prescribed, but the infection did not resolve, the lameness was persistent, and the osteotomy became a nonunion. The patient was euthanized after developing a T3-L3 myelopathy suspected to be related to systemic infection.

Figure 2 Radiographs from an 8-year-old spayed Rottweiler that underwent TPLO and was diagnosed with a superficial SSI 2 weeks postoperatively at another hospital. The SSI was treated with a 10-day course of antibiotics. The dog was presented to The Ohio State University Veterinary Hospital 6 weeks after surgery for recurrent lameness; the incision was healed, but osteomyelitis was confirmed on radiographs and fine-needle aspirate and cytology. Culture-based antibiotics were prescribed, but the infection did not resolve, the lameness was persistent, and the osteotomy became a nonunion. The patient was euthanized after developing a T3-L3 myelopathy suspected to be related to systemic infection.

Figure 2 Radiographs from an 8-year-old spayed Rottweiler that underwent TPLO and was diagnosed with a superficial SSI 2 weeks postoperatively at another hospital. The SSI was treated with a 10-day course of antibiotics. The dog was presented to The Ohio State University Veterinary Hospital 6 weeks after surgery for recurrent lameness; the incision was healed, but osteomyelitis was confirmed on radiographs and fine-needle aspirate and cytology. Culture-based antibiotics were prescribed, but the infection did not resolve, the lameness was persistent, and the osteotomy became a nonunion. The patient was euthanized after developing a T3-L3 myelopathy suspected to be related to systemic infection.

Residual Instability

Cranial-caudal stifle instability is present postoperatively in one-third of TPLO-treated patients.14 Though the majority of dogs with postoperative instability are nonclinical, even nonclinical residual instability may result in a reduced long-term outcome. A more severe instability known as pivot shift, which involves cranial tibial subluxation coupled with a sudden lateral motion of the stifle during weight bearing, occurs in up to 3% of cases.7,12 The cause of residual instability has been hypothesized to be related to meniscectomy (or meniscal release) or incomplete plateau leveling.12,14 Incorrect osteotomy position (eg, osteotomy is positioned distally; Figure 3) or plateau rock-back can affect success in achieving or maintaining plateau leveling and therefore may affect stifle stability.1 In some cases, stifle instability after TPLO (including pivot shift) may resolve with time,8 likely due to improved muscular strength, which may support the hypothesis that some degree of instability can occur due to muscle weakness and further support the recommendation for postoperative physical therapy.

Immediate postoperative radiographs from a 2-year-old spayed medium-size crossbreed dog showing an inappropriately distally positioned TPLO. Distalizing the TPLO reduces the leveling achieved with planned rotation, leaves a narrow tibial crest (arrow), and positions the osteotomy in diaphyseal bone (slower to heal than metaphyseal bone). Also notable is the cranial position of the distal jig pin hole, which may predispose the patient to tibial diaphyseal fracture. This osteotomy position can be compared with that shown in Figure 4, in which the osteotomy position and resultant crest shape are appropriate.
Immediate postoperative radiographs from a 2-year-old spayed medium-size crossbreed dog showing an inappropriately distally positioned TPLO. Distalizing the TPLO reduces the leveling achieved with planned rotation, leaves a narrow tibial crest (arrow), and positions the osteotomy in diaphyseal bone (slower to heal than metaphyseal bone). Also notable is the cranial position of the distal jig pin hole, which may predispose the patient to tibial diaphyseal fracture. This osteotomy position can be compared with that shown in Figure 4, in which the osteotomy position and resultant crest shape are appropriate.

Figure 3 Immediate postoperative radiographs from a 2-year-old spayed medium-size crossbreed dog showing an inappropriately distally positioned TPLO. Distalizing the TPLO reduces the leveling achieved with planned rotation, leaves a narrow tibial crest (arrow), and positions the osteotomy in diaphyseal bone (slower to heal than metaphyseal bone). Also notable is the cranial position of the distal jig pin hole, which may predispose the patient to tibial diaphyseal fracture. This osteotomy position can be compared with that shown in Figure 4, in which the osteotomy position and resultant crest shape are appropriate.

Figure 3 Immediate postoperative radiographs from a 2-year-old spayed medium-size crossbreed dog showing an inappropriately distally positioned TPLO. Distalizing the TPLO reduces the leveling achieved with planned rotation, leaves a narrow tibial crest (arrow), and positions the osteotomy in diaphyseal bone (slower to heal than metaphyseal bone). Also notable is the cranial position of the distal jig pin hole, which may predispose the patient to tibial diaphyseal fracture. This osteotomy position can be compared with that shown in Figure 4, in which the osteotomy position and resultant crest shape are appropriate.

Medial Meniscal Tears

Meniscal pathology causes lameness and progression of osteoarthritis; therefore, intra-articular examination at the time of TPLO is necessary for the diagnosis and treatment of concurrent meniscal pathology. In the months following TPLO, postoperative meniscal tears are diagnosed in 1.8% to 10.5% of cases in which the meniscus was classified as normal and left untreated at the time of TPLO.6,15,16 Some of these cases likely represent meniscal tears that were present but not identified at the time of original surgery. The sensitivity of detecting meniscal tears can be increased by using arthroscopy (vs arthrotomy) and by using a stifle distractor and meniscal probe during joint examination.1,16,17 Development of a postoperative meniscal tear is likely related to the presence of residual stifle joint instability and often results in persistent lameness, requiring an additional procedure for meniscal debridement.

Patellar Tendinosis

Patellar tendon thickening (Figure 4) is a benign process that occurs in 80% to 100% of dogs after TPLO.18 In up to 7% of cases, this thickening is associated with pain and lameness (patellar tendinosis).18 Patellar tendinosis usually responds to NSAIDs and rest, followed by gradual return to activity,18 with anecdotal evidence also supporting the use of shockwave therapy and physical rehabilitation therapy.

Radiographs from a 7-year-old spayed golden retriever presented with recurrent lameness 3 months after TPLO. A moderate weight-bearing lameness and pain on palpation of the cranial stifle/patellar tendon was identified on examination of the operated limb. Radiographs revealed thickening of the patellar tendon (solid arrows) and an apical patellar fracture (dashed arrow). Lameness resolved with rest, NSAID therapy, and shockwave therapy.
Radiographs from a 7-year-old spayed golden retriever presented with recurrent lameness 3 months after TPLO. A moderate weight-bearing lameness and pain on palpation of the cranial stifle/patellar tendon was identified on examination of the operated limb. Radiographs revealed thickening of the patellar tendon (solid arrows) and an apical patellar fracture (dashed arrow). Lameness resolved with rest, NSAID therapy, and shockwave therapy.

Figure 4 Radiographs from a 7-year-old spayed golden retriever presented with recurrent lameness 3 months after TPLO. A moderate weight-bearing lameness and pain on palpation of the cranial stifle/patellar tendon was identified on examination of the operated limb. Radiographs revealed thickening of the patellar tendon (solid arrows) and an apical patellar fracture (dashed arrow). Lameness resolved with rest, NSAID therapy, and shockwave therapy.

Figure 4 Radiographs from a 7-year-old spayed golden retriever presented with recurrent lameness 3 months after TPLO. A moderate weight-bearing lameness and pain on palpation of the cranial stifle/patellar tendon was identified on examination of the operated limb. Radiographs revealed thickening of the patellar tendon (solid arrows) and an apical patellar fracture (dashed arrow). Lameness resolved with rest, NSAID therapy, and shockwave therapy.

Intra-Articular Screw Placement

Intra-articular screw placement likely leads to persistent pain and hastened osteoarthritis development if not addressed immediately. The incidence of intra-articular screw placement during TPLO ranges from <0.1% to 7.1%.6,12,19,20 In one study comparing the use of locking and nonlocking TPLO plates, nonlocking TPLO plates were associated with an increased risk for intra-articular screw placement; this is likely because locking TPLO plates are typically precontoured with a screw trajectory designed to minimize the risk of intra-articular or intra-osteotomy screw placement.20 However, poor plate positioning, intraoperative plate contouring, or cross-threading can affect screw trajectory and result in intra-articular screw placement when using locking plates (Figure 5).20 Postoperative radiographs must be scrutinized for intra-articular screws, and offending screws must be immediately redirected or shortened to prevent the long-term effects of this complication.

Radiographs from a 5-year-old neutered male Bernese mountain dog with persistent lameness 2 months following TPLO. Radiographs revealed the proximal-most screw violating the joint space (arrow). This is best visualized on the third (oblique) view and was not identified on immediate postoperative radiographs. The locking plate is designed to reduce the risk of intra-articular screw placement, but this plate was contoured intraoperatively to accommodate for excessive medial buttress, which resulted in a screw trajectory directed toward the joint space.
Radiographs from a 5-year-old neutered male Bernese mountain dog with persistent lameness 2 months following TPLO. Radiographs revealed the proximal-most screw violating the joint space (arrow). This is best visualized on the third (oblique) view and was not identified on immediate postoperative radiographs. The locking plate is designed to reduce the risk of intra-articular screw placement, but this plate was contoured intraoperatively to accommodate for excessive medial buttress, which resulted in a screw trajectory directed toward the joint space.

Figure 5 Radiographs from a 5-year-old neutered male Bernese mountain dog with persistent lameness 2 months following TPLO. Radiographs revealed the proximal-most screw violating the joint space (arrow). This is best visualized on the third (oblique) view and was not identified on immediate postoperative radiographs. The locking plate is designed to reduce the risk of intra-articular screw placement, but this plate was contoured intraoperatively to accommodate for excessive medial buttress, which resulted in a screw trajectory directed toward the joint space.

Figure 5 Radiographs from a 5-year-old neutered male Bernese mountain dog with persistent lameness 2 months following TPLO. Radiographs revealed the proximal-most screw violating the joint space (arrow). This is best visualized on the third (oblique) view and was not identified on immediate postoperative radiographs. The locking plate is designed to reduce the risk of intra-articular screw placement, but this plate was contoured intraoperatively to accommodate for excessive medial buttress, which resulted in a screw trajectory directed toward the joint space.

Uncommon Complications

The following complications are uncommon but can be catastrophic and therefore warrant individual discussion. Poor surgical technique will increase the incidence of these complications.

Plateau Rock-Back

Rock-back (ie, loss of plateau leveling) results from failure—sometimes catastrophic—of the plate, screws, and/or plateau segment. Some studies report more loss of osteotomy reduction in the postoperative period when nonlocking constructs are used as compared with locking constructs.21 Rock-back can affect long-term outcome if it results in recurrent stifle instability. Implant or bone failure can occur with use of either nonlocking or locking constructs in cases of poor surgical technique (eg, poor osteotomy position, incomplete osteotomy compression, improper plate/screw position or application) or incomplete postoperative activity restriction and can have catastrophic consequences.

Tibial Tuberosity Fracture

The risk for tibial tuberosity fracture may be increased by an osteotomy position that results in a narrow crest (Figure 3), by bilateral simultaneous TPLO procedures, or by other factors that either decrease the strength of the patellar tendon’s anchor point or increase the pull of the patellar tendon.7,22 Many cases do not require intervention, although surgical stabilization may be required if the fragment is unstable.

Fibular Fracture

Inadvertent drilling of the fibula during TPLO increases the risk for fibular fracture 10-fold. Although it is suspected that the risk for fracture is higher when the fibular drill hole is left unfilled—and therefore it is recommended to fill the hole—this was not proven statistically (likely a type II statistical error).23 Increased body weight is also a risk factor for fibular fracture after TPLO.23 Fibular fracture eliminates the fibula’s splinting function, which likely aids in stabilizing the osteotomy and, therefore, fibular fractures may increase the incidence and degree of rock-back.23

Patellar Luxation

Patellar luxation occurs in <1% of cases following TPLO, although in one study, the majority of postoperative patellar luxations required revision surgery.7,15 The theorized causes of patellar luxation as a complication of TPLO include muscle atrophy, closure of the medial retinaculum under too much or too little tension, severe joint effusion after surgery, and creation of tibial malalignment.15

Other Complications

Additional complications to consider include anesthetic complications, minor incisional complications (eg, minor dehiscence, seroma, suture reaction), intraoperative hemorrhage (arterial), delayed/nonunion, implant failure, tibial diaphyseal fracture, creation of angular deformity, collateral ligament or patellar tendon trauma, and implant-associated sarcomas.7,15,24

Conclusion

Preventing complications during recovery depends on both preoperative and intraoperative decision making, along with owner education and compliance. Owners must be instructed to keep Elizabethan collars on their pet until the incision is healed. For ≈8 weeks following surgery, or until radiographic healing is demonstrated, patient activity should be strictly controlled; no concussive activity or free roaming should be allowed, but gradually increasing duration of leashed walking and other controlled strengthening exercises is important to promote muscular recovery and bone healing. Adhering to these strict guidelines should mitigate the risk for incisional complications, implant and bone failure, and delayed healing.

CrCL = cranial cruciate ligament, CrCLR = cranial cruciate ligament rupture, SSI = surgical site infection, TPLO = tibial plateau-leveling osteotomy

References

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Digital Edition may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.


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Leptospirosis

J. Scott Weese, DVM, DVSc, DACVIM, Ontario Veterinary College, Ontario, Canada

Infectious Disease

|Peer Reviewed

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Leptospirosis
Clinician's Brief
Clinician's Brief
* Utility of PCR is low if antimicrobials were started before specimen collection.

Leptospirosis Management

Once leptospirosis diagnosis is confirmed, patients should be treated with antimicrobials and supportive care as needed.

Antimicrobials

  • If the patient can tolerate oral medication: Doxycycline (5 mg/kg PO every 12 hours) for 14 days1
  • If the patient cannot tolerate oral medication: Ampicillin (20 mg/kg IV every 6 hours), then, if possible, de-escalated to oral doxycycline (5 mg/kg PO every 12 hours) for an additional 14 days1

Supportive Care

  • IV fluids for replacement, diuresis, acid-base balance, and electrolyte maintenance
  • Antiemetics
  • Nutritional support for renal or hepatic injury
  • Renal replacement therapy can be considered in oliguric dogs developing volume overload, severe hyperkalemia, or severe azotemia nonresponsive to medical management.1
  • Other care as needed based on clinical syndrome and patient response to treatment

During hospitalization, hydration status should be carefully monitored (ie, measure “ins and outs,” thoracic auscultation, blood pressure), as should BUN/creatinine, acid-base/electrolytes, ± hepatic enzymes (as often as every 24 hours initially). PCV should be rechecked as often as every 24 hours initially, and CBC should be repeated as often as every 48 hours if thrombocytopenia is present and/or in severe cases. Urine specific gravity should also be rechecked every few days once fluid therapy has been discontinued, and clotting factors should be rechecked if abnormal.

Approximately 1 week after the patient is discharged, serum chemistry profile should be repeated, as should CBC if abnormalities were present at the time of discharge. Serum chemistry profile should be rechecked again in 3 to 7 days if results are still abnormal. Urine specific gravity should be monitored regularly if abnormal.

Table

LEPTOSPIROSIS TESTS & CONSIDERATIONS

Test Target Sample type Patient-side? Impacted by vaccination? Impacted by antimicrobial treatment?
MAT Antibody (IgM and IgG) Serum No Yes No
Lepto rapid test Antibody (IgM) Serum Yes Yes No
LipL-32 Leptospira Antibody (IgG>IgM) Serum Yes Yes No
PCR Antigen Urine, whole blood No No Potentially

IgG = immunoglobulin G, lgM = immunoglobulin M, MAT = microscopic agglutination test

References

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Digital Edition may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.


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Differential Diagnosis: Proteinuria in Dogs

Barry Hedgespeth, BVSc, North Carolina State University

Karyn Harrell, DVM, DACVIM, North Carolina State University

Urology & Nephrology

|Peer Reviewed

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Differential Diagnosis: Proteinuria in Dogs

Following are differential diagnoses for dogs presented with proteinuria.

Prerenal

  • Hemoglobinuria
  • Myoglobinuria
  • Light chain immunoglobulins (multiple myeloma, lymphoma)

Renal

  • Functional or physiologic
    • Congestive heart failure
    • Strenuous exercise
    • Fever
    • Seizure
    • Exposure to extreme temperatures 
  • Glomerular
    • Infection
      • Bacterial (eg, anaplasmosis, borreliosis, bartonellosis, brucellosis, endocarditis, pyelonephritis, pyometra, pyoderma, Rocky Mountain spotted fever, other chronic infections)
      • Protozoal (eg, babesiosis, hepatozoonosis, leishmaniasis, trypanosomiasis)
      • Viral (eg, canine adenovirus type 1)
      • Parasitic (eg, dirofilariasis, schistosomiasis)
      • Fungal (eg, blastomycosis, coccidioidomycosis, histoplasmosis, phaeohyphomycosis)
    • Inflammatory
      • Chronic dermatitis
      • Inflammatory bowel disease
      • Acute pancreatitis 
      • Periodontal disease
      • Polyarthritis
      • Systemic lupus erythematosus
      • Other immune-mediated disease
    • Neoplastic
      • Leukemia
      • Lymphoma
      • Mastocytosis
      • Primary erythrocytosis/polycythemia vera
      • Systemic histiocytosis
    • Congenital or familial
      • Amyloidosis (eg, beagle, English foxhound, shar-pei)
      • Hereditary nephritis (eg, bull terrier, cocker spaniel, Dalmatian, Samoyed)
      • Podocytopathy (soft-coated wheaten terrier)
      • Membranoproliferative glomerulonephritis (Bernese mountain dog)
      • Atrophic glomerulopathy (rottweiler)
    • Miscellaneous 
      • Corticosteroids (endogenous/spontaneous hyperadrenocorticism or exogenous)
      • Diabetes mellitus
      • Systemic hypertension 
      • Hyperlipidemia
      • Drug reactions (eg, sulfonamide [eg, sulfa-/trimethoprim] therapy, masitinib)
      • Chronic insulin infusion
      • Congenital C3 deficiency
      • Cyclic hematopoiesis (ie, gray collie syndrome)
  • Tubulointerstitial
    • Chronic kidney disease (including congenital/familial conditions such as renal dysplasia and polycystic kidney disease)
    • Acute kidney injury
      • Leptospirosis
      • Toxins (eg, NSAIDs, grapes, raisins, currants, ethylene glycol, vitamin D3, aminoglycosides, amphotericin B, sulfonamide [eg, sulfa-/trimethoprim] therapy, tyrosine kinase inhibitors [toceranib phosphate, masitinib mesylate] heavy metal ingestion [eg, lead, mercury, arsenic, thallium], insect or snake bite)
    • Fanconi syndrome
    • Interstitial nephritis

Postrenal

  • Urinary
    • Bacterial cystitis
    • Urolithiasis
    • Neoplasia (eg, urothelial carcinoma)
  • Extra-urinary
    • Prostatitis
    • Vaginitis
    • Pyometra

References

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Digital Edition may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.


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AHS CB AprilMay 2021

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Orthomed CB AprilMay 2021

Comparing Bacterial Communities on Skin of Healthy & Allergic Cats

William Oldenhoff, DVM, DACVD, Madison Veterinary Specialists in Monona, Wisconsin

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Comparing Bacterial Communities on Skin of Healthy & Allergic Cats

In the literature

Older CE, Diesel AB, Starks JM, Lawhon SD, Hoffmann AR. Characterization of staphylococcal communities on healthy and allergic feline skin. Vet Dermatol. 2021;32(1):61-e10.


FROM THE PAGE…

Relatively little is known about the normal microbial populations on the skin of cats as compared with that of humans and dogs. In this study, researchers investigated the staphylococcal communities on the skin of healthy and allergic cats. Skin swabs were obtained from the ear canal and groin of 11 healthy cats and 10 allergic cats. Skin samples from allergic cats were free of skin lesions. DNA was extracted from the samples and sequenced using a region of the 16S rRNA gene. Predominant phyla found included Proteobacteria (average relative abundance 52.29%), Firmicutes (17.94%), Actinobacteria (13.99%), and Bacteroidetes (11.87%). Overall abundance of Staphylococcus spp was fairly low, with an average abundance of 4.34% in healthy cats and 3.61% in allergic cats. Samples with staphylococcal sequences often had multiple different species, with an average of 2 species per sample. S epidermidis and S pseudintermedius were most common in samples from healthy cats, and S capitis and S felis were most common in samples from allergic cats. S pseudintermedius was only identified in 4 sequences from allergic cats. No significant difference in microbial diversity was found between healthy and allergic cats.


…TO YOUR PATIENTS

Key pearls to put into practice:

1

Diverse populations of Staphylococcus spp exist in cats. This differs from dogs, in which S pseudintermedius is the predominant species found in both healthy and allergic patients. This finding provides evidence for different clinical considerations in management of dogs and cats.

2

Differences in flora detected between healthy and allergic patients may represent targets for therapeutic intervention. In this study, significant differences were not found in the cutaneous microbiota of healthy and allergic cats; however, because the study sampled nonlesional skin of allergic cats, it is possible that lesional skin of allergic cats may have different microbiota.

3

Although statistical significance was not achieved, some differences were observed between healthy and allergic feline skin. S epidermidis was more common on the skin of healthy cats as compared with allergic cats. This is also found in humans, in which S epidermidis is more common on healthy human skin and can have a protective role in skin health.1 Further research is needed to determine if a similar protective role can be documented in cats.

References

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Digital Edition may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.


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Elura CB AprilMay 2021

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Purevax CB AprilMay 2021

Sedation in African Pygmy Hedgehogs

Angela M. Lennox, DVM, DABVP, Avian & Exotic Animal Clinic, Indianapolis, Indiana

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Sedation in African Pygmy Hedgehogs

In the literature

Hawkins SJ, Doss GA, Mans C. Evaluation of subcutaneous administration of alfaxalone-midazolam and ketamine-midazolam as sedation protocols in African pygmy hedgehogs (Atelerix albiventris). J Am Vet Med Assoc. 2020;257(8):820-825.


FROM THE PAGE…

African pygmy hedgehogs almost always require immobilization to undergo complete physical examination. This species is prone to neoplasia1,2; thus, examination should be thorough and include careful inspection of the oral cavity, as well as abdominal palpation.

Anecdotally, immobilization is often accomplished via chamber induction with inhalation agents. Although chamber induction may seem safe, it can be stressful in many species (including rodents and rabbits) and can increase staff exposure to anesthetic waste gas.3 Clinician resistance to injectable sedative agents may be due to perceived difficulties in injecting conscious hedgehogs or the desire to limit time between presentation and discharge.

This blinded crossover study compared 2 SC sedation protocols in hedgehogs: ketamine (30 mg/kg) in conjunction with midazolam (1 mg/kg) and alfaxalone (3 mg/kg) in conjunction with midazolam (1 mg/kg). Various physiological parameters were measured. Flumazenil (0.05 mg/kg SC) was administered 45 minutes after sedation for midazolam reversal. Although SC administration was not discussed, SC and intramantle injection are typically easy to accomplish (Figure).

Both protocols resulted in sedation levels that would likely allow for thorough physical examination and optimal positioning for diagnostic imaging. Time to loss of righting response, duration of effects, and recovery time after flumazenil administration did not differ significantly.

Sedation with ketamine and midazolam was less consistent than with alfaxalone and midazolam, as not every patient completely lost the righting response, and there were more pronounced effects on body weight and food intake in the 6 days after sedation. Further, because of ketamine’s acidic pH, this drug can cause more pain on injection as compared with alfaxalone.

Intramantle injection of a combination of drugs used for sedation in an African pygmy hedgehog
Intramantle injection of a combination of drugs used for sedation in an African pygmy hedgehog

FIGURE Intramantle injection of a combination of drugs used for sedation in an African pygmy hedgehog

FIGURE Intramantle injection of a combination of drugs used for sedation in an African pygmy hedgehog


…TO YOUR PATIENTS

Key pearls to put into practice:

1

A complete physical examination in African pygmy hedgehogs almost always requires immobilization. Thorough examination is essential because of the species’ high incidence of neoplasia.

2

Although inhalation agents via chamber induction are commonly used for sedation, injectable agents are a viable option that likely reduce stress and decrease staff exposure to anesthetic waste gas.

3

Both protocols discussed in this study provided adequate sedation for thorough physical examination and, likely, optimal positioning for diagnostic imaging and were apparently safe.

 

4

The author uses alfaxalone (1-3 mg/kg), midazolam (0.5-1 mg/kg), and butorphanol (0.2 mg/kg) for sedation, with additional 1 mg/kg alfaxalone boluses as indicated. Although recovery is not as rapid as with inhalation chamber induction, most patients are ready for discharge within 30 to 45 minutes after reversal with flumazenil.

References

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Digital Edition may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.


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NVA CB AprilMay 2021

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Sentinel CB AprilMay 2021

Potential Novel Treatment for Canine Pemphigus Foliaceus

William Oldenhoff, DVM, DACVD, Madison Veterinary Specialists in Monona, Wisconsin

Dermatology

|Web-Exclusive

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Potential Novel Treatment for Canine Pemphigus Foliaceus

In the literature

Goodale EC, White SD, Bizikova P, et al. Open trial of Bruton's tyrosine kinase inhibitor (PRN1008) in the treatment of canine pemphigus foliaceus. Vet Dermatol. 2020;31(5):410-e110.


FROM THE PAGE …

This study* evaluated the efficacy of a Bruton’s tyrosine kinase (BTK) inhibitor in the treatment of canine pemphigus foliaceus. BTK is necessary for B-cell development, and autoreactive B cells are particularly dependent on BTK for survival as compared with normal B cells.1 Autoreactive B cells produce autoantibodies, which contribute to various autoimmune diseases. Canine pemphigus foliaceus is characterized by production of antibodies directed primarily against desmocollin-1, a component of desmosomes. When BTK is absent, autoantibodies are lost and total antibody levels are unchanged. Because of this targeted effect, BTK inhibition is an appealing candidate in the treatment of humorally mediated autoimmune diseases (eg, pemphigus foliaceus).

The BTK inhibitor, BTKi PRN1008 (also called rilzabrutinib), was evaluated in the treatment of 4 dogs with pemphigus foliaceus. Initial doses of 15 mg/kg PO once daily were used, with administration increased to twice daily if inadequate response was noted. Final daily doses were in the range between 17 mg/kg and 33 mg/kg. All dogs showed improvement within the first 2 weeks of treatment, and 3 dogs were near remission by 20 weeks. The remaining dog achieved a fair response. After treatment, anti-desmocollin-1 immunoglobulin G was measured and determined to be absent in 2 dogs, reduced in 1 dog, and uninterpretable in 1 dog. An 8-year-old intact female developed pyometra during the study, but it is not clear whether this was related to rilzabrutinib. The same dog had elevated ALT and AST, both of which returned to normal when the dose was decreased.


…TO YOUR PATIENTS

Key pearls to put into practice:

1

Pemphigus foliaceus is a challenging disease to treat. In most cases, high doses of systemic steroids are needed to induce remission. This is typically followed by a gradual dose reduction to the lowest steroid dose that maintains remission of disease. Frequently, nonsteroidal immunosuppressive drugs are also used to allow further reduction of the steroid dose.

2

Steroids have a variety of common adverse effects, which can be challenging to manage, especially in patients that require ongoing immunosuppression, as is the case in most dogs with pemphigus foliaceus. Nonsteroidal immunosuppressive drugs also have the potential for serious adverse effects. Thus, there is a need for novel targeted therapies in dogs with pemphigus foliaceus.

3

Rilzabrutinib is promising, as it was able to induce remission in 3 of the 4 study dogs. There were few adverse effects, but the study was limited by the small number of dogs enrolled. In addition, the study took place over 20 weeks, but most dogs with pemphigus foliaceus require ongoing, lifelong therapy. It is not known whether longer courses of rilzabrutinib may be associated with more adverse effects. Further study will be needed to determine if rilzabrutinib is a good long-term alternative to steroids in the treatment of pemphigus foliaceus.

*This study was funded by Principia Biopharma.

References

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Digital Edition may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.


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Epicur CB AprilMay 2021

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Dechra CB AprilMay 2021

Assessing Cats with Vehicular Trauma

Amanda Abelson, DVM, DACVAA, DACVECC, Cummings School of Veterinary Medicine at Tufts University

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Assessing Cats with Vehicular Trauma

In the literature

Lyons BM, Ateca LB, Otto CM. Clinicopathological abnormalities associated with increased animal triage trauma score in cats presenting for vehicular trauma: 75 cases (1998–2009). J Vet Emerg Crit Care (San Antonio). 2020;30(6):693-697.


FROM THE PAGE…

Cats are commonly presented due to vehicular trauma. Rapid assessment is needed to provide appropriate emergency therapy and accurate prognosis. The animal trauma triage (ATT) score can be used to characterize disease severity and help predict outcome after traumatic insult. The ATT score is calculated based on physical examination abnormalities in 6 categories: perfusion, cardiac, respiratory, skeletal, neurologic, and eye/muscle/integument. The total ATT score ranges from 0 to 18, with higher values signifying greater severity of trauma, and can be performed by an experienced clinician or veterinary nurse. The ATT score has been validated in dogs and cats to demonstrate that for each 1-point increase, survival decreases 2.3 to 2.6 times1; in dogs, an ATT score of ≥5 has been associated with 83% sensitivity and 91% specificity in predicting nonsurvival.2

This retrospective study investigated whether a correlation exists between ATT and clinicopathologic alterations in cats presented following vehicular trauma. The study included 75 cats divided into 2 groups: cats with an ATT score ≥5 (n = 45) and cats with an ATT score <5 (n = 30). Differences in emergency point-of-care blood work (including packed cell volume [PCV], total protein, glucose, venous blood pH, plasma bicarbonate, base excess, venous partial pressure of carbon dioxide, plasma lactate, sodium, potassium, chloride, ionized calcium, ionized magnesium, BUN, and creatinine), Doppler blood pressure, and patient outcome were evaluated. Cats with an ATT score ≥5 had lower PCV, total plasma protein concentration, venous blood pH, base excess values, plasma bicarbonate concentrations, and Doppler blood pressure values, as well as higher glucose and lactate values. This group also had a higher mortality rate (57.8%) as compared with the second group (10%).

This study showed that the ATT score and emergency point-of-care blood work can be used to identify cats with more serious injury at the time of presentation. This may aid in providing appropriate therapy and determining prognosis.


…TO YOUR PATIENTS

Key pearls to put into practice:

1

The ATT score has been validated in both dogs and cats, is typically easy to determine because it is based on physical examination findings, and can be helpful in determining prognosis.

 

2

Cats with an ATT score ≥5 often have the following clinicopathologic changes as compared with cats that have an ATT score <5: lower PCV, total protein levels, blood pH, plasma bicarbonate concentration, base excess values, and Doppler blood pressure values, as well as higher blood glucose and lactate values.

3

Cats presented after vehicular trauma and that have an ATT score ≥5, or the blood work alterations listed directly above, should be suspected of having significant traumatic injury.

References

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Digital Edition may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.


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Galliprant CB AprilMay 2021

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iM3 CB AprilMay 2021

Predicting Infection in Acute Traumatic Wounds

Jonathan Miller, DVM, MS, DACVS (Small Animal), Oradell Animal Hospital, Paramus, New Jersey

Surgery, Soft Tissue

|Web-Exclusive

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Predicting Infection in Acute Traumatic Wounds

In the Literature

Hamil LE, Smeak DD, Johnson VA, Dow SW. Pretreatment aerobic bacterial swab cultures to predict infection in acute open traumatic wounds: A prospective clinical study of 64 dogs. Vet Surg. 2020;49(5):914-922.


FROM THE PAGE…

Infection development in wounds is common in veterinary patients. Predicting time of infection occurrence can assist in judicious antibiotic use. This study examined bacterial culture results in dogs with wounds caused by bites or other acute cutaneous trauma. Cultures were taken before and after wound lavage with lactated Ringer’s solution.1

The primary objective of this study was to assess the type and quantity of bacteria present in the wound before and after lavage. The secondary objective was to evaluate whether culture results were useful for predicting ultimate wound infection. Size, type, and treatment of wounds by closure were examined in 64 dogs.

The rate of positive culture results significantly decreased from 76.6% before lavage to 56.3% after lavage, with an 86% reduction in the number of bacteria after irrigation. The species of bacteria grown in cultures were the same in 70.3% and different in 29.7% of wounds after lavage. Typical bacteria were Staphylococcus spp, Streptococcus spp, and Pasteurella spp. Although all dogs received a β-lactam antibiotic, 21.9% of wounds developed at least 1 sign of clinical infection during the 30-day follow-up. Postinfection cultures predominantly yielded Staphylococcus spp, Escherichia coli, and Pseudomonas spp, of which 69.2% were resistant to the prescribed prophylactic β-lactam antibiotic.

No relationship was found between development of clinical infection and prelavage culture, postlavage culture, number of bacteria cultured, or the wound size, type, or treatment. Although the reduction in bacteria after wound lavage was encouraging, the lack of reliable predictable factors for developing wound infection is a good reminder of the unpredictable nature of these cases.


… TO YOUR PATIENTS

Key pearls to put into practice:

1

Wound lavage with lactated Ringer’s solution is effective for reducing bacterial load.

2

Cultures collected either before or after lavage do not appear to be helpful in predicting whether a wound will become infected or with which bacteria.

 

3

Resistance to prophylactic antibiotics is common in infected wounds.

 

4

Wound size, cause, and treatment after lavage do not seem to be useful in predicting infection.

References

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Digital Edition may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.


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Revolution CB AprilMay 2021

Effects of Hetastarch on Colloid Osmotic Pressure

Amanda A. Cavanagh, DVM, DACVECC, Colorado State University

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Effects of Hetastarch on Colloid Osmotic Pressure

In the Literature

Borrelli A, Maurella C, Lippi I, et al. Evaluation of the effects of hydroxyethyl starch (130/0.4) administration as a constant rate infusion on plasma colloid osmotic pressure in hypoalbuminemic dogs. J Vet Emerg Crit Care. 2020;30(5):550-557. 


FROM THE PAGE…

This study sought to investigate the effects of 2 CRIs of hydroxyethyl starch (HES) on plasma colloid osmotic pressure (COP) in dogs with hypoalbuminemia. A total of 24 dogs were included in the study. Dogs were randomly placed into 2 groups and given a synthetic colloid (HES 130/0.4, 1 mL/kg/hour CRI or 2 mL/kg/hour CRI for 24 hours). Causes of hypoalbuminemia varied and included diarrhea, chylothorax, protein-losing nephropathy, septic peritonitis, and hypoadrenocorticism. No difference was found in measured COP over time between the groups, and there was no discussion on the clinical effect of these infusions.

Intravascular hydrostatic pressure promotes fluid extravasation, and intravascular osmotic pressure opposes extravasation. COP (ie, oncotic pressure) is the portion of osmotic pressure attributed to plasma proteins (albumin accounts for ≈80% of COP)1 and is dictated by the concentration of molecules in the solution, not the size of molecules. However, because colloids do not readily cross the vascular endothelium, due in part to size, these molecules increase COP by remaining in the intravascular space. Synthetic colloids are intravenous fluids manufactured with high molecular weight particles (eg, hetastarch, tetrastarch) that have the potential to increase COP and remain within the vascular space.

The modified Starling equation expresses the balance between osmotic and hydrostatic pressures governing fluid flux across the endothelium but does not represent all contributing factors to fluid movement. The endothelial glycocalyx (a meshwork of membrane-bound proteoglycans and glycoproteins lining the luminal surface of the endothelium2) is crucial to vascular integrity in health and disease. Soluble plasma molecules, including plasma proteins, dynamically integrate into and shed from the endothelial surface layer. Trauma, sepsis, and low protein environments, along with other pathologies, can rapidly lead to glycocalyx shedding.3 Loss of the glycocalyx typically results in abnormal vascular permeability and fluid extravasation.2,3 Synthetic colloids administered in the presence of a degraded glycocalyx can extravasate and accumulate in the interstitium; they do so more readily than natural colloids, eliminating the intended positive effect on COP.3 Natural colloids (eg, albumin solutions, plasma transfusion) are more effective at restoring the glycocalyx.3

It is difficult to draw clinical conclusions from these study findings. Patients received variable volumes of concurrent crystalloid fluids that could have a dilutional effect on COP. Given their underlying diseases, these patients may have had an abnormal glycocalyx, leading to the loss of HES 130/0.4 molecules into the interstitium, with no net overall effect on COP. Because of the crucial role of the glycocalyx, measured COP is unlikely to predict the volume-expanding effects of a colloid. Although synthetic colloids are readily available, affordable, and can be stored safely, their use includes the risk for acute kidney injury, coagulopathy, and unfulfilled expectations of vascular expansion.4-6


…TO YOUR PATIENTS

Key pearls to put into practice:

1

Natural colloids (eg, canine albumin solution, plasma transfusion) can be considered in patients with hypoproteinemia that need fluid therapy and COP support.7 Natural colloids are more effective at restoring the glycocalyx and vascular integrity.

2

Synthetic colloids should be used at the lowest effective dose for the shortest period of time possible. Prolonged use of synthetic colloids increases the risk for acute kidney injury in dogs.4

 

3

Synthetic colloids should not be used in patients with suspected or documented sepsis due to the risk for acute kidney injury; however, this originates from human guidelines and has not been proven in veterinary patients.

References

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Digital Edition may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.


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PVD CB AprilMay 2021

Research Note: Homocysteine in Feline Chronic Kidney Disease

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Although chronic kidney disease (CKD) is one of the most common diseases that affects elderly cats, few tests are currently recommended for diagnosing early-stage CKD and forecasting disease progression. In humans and dogs, homocysteine (Hcy) has been associated with certain aspects of renal dysfunction, including a positive correlation to systolic blood pressure in humans. Because it can be difficult to obtain blood pressure readings and to predict and track early renal disease in hospitalized cats, the authors investigated the potential applications of Hcy in feline CKD diagnostics. In this study, Hcy increases could be correlated to International Renal Interest Society (IRIS) stage; however, significant differences between IRIS groups were not always present. A significant difference was not found between concentration of Hcy and degree of proteinuria, and no correlation was found between high Hcy levels and hypertension. Thus, the authors concluded that serum creatinine provides more reliable information than Hcy concentration for purposes of early identification and staging of CKD in cats.

Source

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Digital Edition may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.


Research Note: Vitamin D in Cats with Liver Disease

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Humans with chronic cholestatic liver disease (CLD) have deficiencies in vitamin D. Cats with inflammatory bowel disease, intestinal small cell lymphoma, and some infections have also been shown to be deficient in vitamin D. This prospective study compared vitamin D levels in cats with CLD with vitamin D levels in cats with nonhepatobiliary illness. Median serum vitamin D levels were similar between the groups, although low vitamin D occurred in a greater percentage of cats with CLD. Lower vitamin D was moderately correlated with higher WBC counts. Further study into the cause and clinical significance of these findings is warranted.

Source

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Digital Edition may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.


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Osurnia CB AprilMay 2021

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Dermabliss CB AprilMay 2021

Anthropologic Insights on Companion Animal Antimicrobial Practices

Jeein Chung, DVM, MPH, DACVPM, Fairfax, Virginia

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Anthropologic Insights on Companion Animal Antimicrobial Practices

In the literature

Tompson AC, Chandler CIR, Mateus ALP, O'Neill DG, Chang Y-M, Brodbelt DC. What drives antimicrobial prescribing for companion animals? A mixed-methods study of UK veterinary clinics. Prev Vet Med. 2020;183:105117.


FROM THE PAGE…

Antimicrobial resistance is a high-priority global health issue with significant relevance to veterinary medicine. Although companion animal clinicians routinely prescribe antibiotics, efforts to understand antimicrobial dispensation practices, as well as attitudes, behaviors, and institutional factors surrounding these practices, are poorly understood.

This study, which analyzed >460,000 antimicrobial dispensing events in dogs across the United Kingdom, provides a nonveterinary, anthropologic perspective that highlights knowledge and behaviors surrounding antimicrobial dispensation that can be taken for granted, breaking clinicians from isolated approaches of antibiotic treatment.

The study found that clinicians in the United Kingdom were unfamiliar with the term “Highest Priority Critically Important Antimicrobials” (HPCIAs), which is used by the World Health Organization to describe antimicrobials that are critically important in human medicine (including fluoroquinolones, quinolones, third-generation and higher cephalosporins, macrolides and ketolides, glycopeptides, and polymyxins).1 In addition, although clinicians are commonly involved in dispensing antimicrobials, they may be less involved in the greater public health conversation.

The study noted a greater likelihood of prescribing HPCIAs (eg, cefovecin—a third-generation, long-acting cephalosporin) to small-breed dogs, as these dogs require a lower dose, which could be less cost-prohibitive. The study also noted that younger clinicians tended to champion prudent antibiotic use but did not feel they could challenge their colleagues, in part due to their relative position in the clinic.

Although the study included robust quantitative and qualitative methods and appropriate use of statistics, some inferences may not be meaningful in practice. For example, the study showed an increased odds ratio of administering HPCIAs to patients of increasing age. However, because these intervals were broken into ≈4-year age intervals (ie, <1.5 years of age, 1.5-4.3 years of age, 4.3-8.2 years of age, and >8.2 years of age), the study did little to signify associations between more meaningful age groups (eg, neonates, juveniles, seniors). The study also could not isolate attitudes and behaviors at the individual clinician level.

Important literature on antimicrobial practices in veterinary medicine (see Suggested Reading) was included. It is important to review such literature for a better understanding of current antimicrobial practices to optimize use of HPCIAs in veterinary medicine.


…TO YOUR PATIENTS

Key pearls to put into practice:

1

HPCIA use should be reconsidered and limited in patients with routine infections, particularly in small-breed patients, in which a lower dosage and subsequent cost may seem beneficial.

 

2

Pet owner education regarding the ongoing public health issue of antimicrobial resistance, including consequences of uncontrolled and improper antibiotic use, is important. Any course of antibiotics should be taken in its entirety, and owners should be assisted (eg, via offering outpatient or at-home services) to ensure compliance when possible.

3

Clinicians should perform culture and susceptibility testing and recommend the most prudent antibiotic therapy for the patient and owner. Although it is up to the clinician to dispense antibiotics, when appropriate, owners should be given a range of antimicrobial therapeutic options so they can make fully informed decisions and maximize compliance.

References

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Digital Edition may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.


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Heartgard CB AprilMay 2021

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Douxo CB AprilMay 2021

Research Note: Diagnostic Value of Various Indexes in Psittacine Birds with Hepatic Disease

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Liver disease is common in psittacine birds, but diagnosis can be challenging. Clinical signs are often nonspecific, and common serum indexes (eg, ALT, AST, ALP, lactate dehydrogenase, creatine phosphokinase) are not tissue-specific to the liver. This retrospective study evaluated the diagnostic value of plasma biochemistry, hematology, radiography, and endoscopic visualization of the liver in 28 pet birds with a diagnosis of liver disease based on histopathology. Investigators found that none of the antemortem diagnostics correlated with biopsy findings, and they concluded that liver biopsy is the best way to diagnose liver disease in psittacine birds, even if the liver is grossly normal.

Source

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Digital Edition may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.


Breaking the Vicious Cycle of Inflammation in Canine Osteoarthritis

Breaking the Vicious Cycle of Inflammation in Canine Osteoarthritis

Steven M. Fox, MS, DVM, MBA, PhD

John M. Donecker, VMD, MS

Orthopedics

|Sponsored

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Breaking the Vicious Cycle of Inflammation in Canine Osteoarthritis
Sponsored by Exubrion Therapeutics, maker of Synovetin OA
Clinician's Brief

FIGURE 1 Arthroscopic view of synovitis, characterized by infiltration of the synovial membrane with inflammatory cells resulting in angiogenesis and hyperplasia of the synovium

KEY POINTS

  • Synovitis likely plays a pivotal role in the pathogenesis of OA, and a multimodal approach to managing OA may provide the best outcomes.
  • Synovetin OA is a groundbreaking new treatment that provides durable relief from the chronic pain and inflammation of canine elbow OA. With 1 fast intraarticular injection, effects last up to 1 year, providing veterinarians and pet owners with a convenient approach to managing chronic pain and inflammation.

Osteoarthritis (OA) affects ≈20% of adult dogs1 and is increasingly understood to be a vicious cycle. Recognizing this can open up new methods of treating this complex condition.1

OA has traditionally been viewed as a cartilage-only disease; however, synovitis (ie, inflammation of the synovium) is a common clinical finding.2 Clinical signs of inflammation, histologic inflammation in osteoarthritic synovial tissue, and early cartilage lesions at the border of the inflamed synovium strongly indicate that synovitis plays a pivotal factor in the pathogenesis of OA.3

Synovial inflammation is implicated in many signs of OA, including joint swelling and effusion. The OA synovium has both inflammatory and destructive responses that depend largely on macrophages. These effects are cytokine-driven primarily through a combination of interleukin-1 and tumor-necrosing factor α.4 Such observations are stimulating increased investigation into dynamic changes within the microenvironment of the synovial joint. The goal of this research is to develop therapies that can decrease both inflammatory synovitis and the production of degradative enzymes, which contribute significantly to the progression of OA.4 With this goal in mind, a new focus for chronic pain management is the macrophage, which acts as the conductor of the inflammatory orchestra.

Inflammation, pain, impaired mobility and function, and structural changes characterize OA and contribute to its progression.5-7 Pain is the hallmark of OA and results in both local and distant deterioration of the musculoskeletal system as a result of decreased and altered mobility. The pathologic process of OA, including joint capsule thickening and periosteal reactions, causes an altered range of motion, compounding musculoskeletal changes. Continual nociceptive input in the CNS results in somatosensory system deterioration and central sensitization with wind-up, amplifying the perception of pain.8 Presently, the functional and structural changes associated with canine OA are incurable.

Pain is the hallmark of OA and results in both local and distant deterioration of the musculoskeletal system as a result of decreased and altered mobility.

Early intervention has the greatest potential for providing the most effective management of OA by providing the opportunity to initiate an appropriate long-term care plan and to disrupt the progressive, vicious cycle of multidimensional deterioration involving both the neurologic and musculoskeletal systems.9 From such recognition has come a proposed instrument for staging canine OA, the Canine OsteoArthritis Staging Tool.9 This tool can help identify OA at an early stage, noting preradiographic changes and improving dog owners’ awareness of early-stage OA. Such clinician/pet owner synergism can help drive earlier and, therefore, more successful treatment by slowing disease progression.

Clinician's Brief

FIGURE 2 The vicious cycle of inflammation. Overview of OA as a process rather than a disease, beginning with synovitis of a synovial joint caused by various sources, including trauma, instability, or idiopathic causes.12-18 Regardless of etiology, histologic changes in the synovium include hyperplastic and hypertrophic synoviocyte changes and robust angiogenesis. Synoviocytes are mostly macrophages, and these changes cause an overproduction of proinflammatory cytokines (eg, matrix metalloproteinases, interleukins, tumor-necrosing factor α) that become part of the joint fluid milieu moving to and from synovial and cartilage tissues as the dog loads and unloads the joint. Matrix metalloproteinases, aggrecanases (metalloproteinases which cleave the aggrecan building blocks of cartilage), and nitric oxide, an important mediator in chondrocyte apoptosis, are particularly destructive to cartilage. With cartilage catabolism comes progressive inflammation, pain, and disability, contributing to the vicious cycle

Synovetin OA® is a groundbreaking new treatment that provides durable relief from the chronic pain and inflammation of canine elbow OA. With 1 fast intra-articular injection, effects last up to 1 full year, providing veterinarians and pet owners with a convenient approach to managing chronic pain and inflammation. By depleting proinflammatory macrophages (the source of chronic pain), Synovetin OA breaks the vicious cycle of inflammation, providing effective, long-lasting, safe, nonsystemic relief. During 3 separate yearlong clinical trials involving 69 client-owned dogs, Synovetin OA was shown to be safe and effective.10 One of these studies also showed Synovetin OA to be safe for re-administration to a previously treated elbow joint.

Optimal-sized homogeneous colloid particles are small enough for engulfment by macrophages, but large enough to remain in the joint space.19
Optimal-sized homogeneous colloid particles are small enough for engulfment by macrophages, but large enough to remain in the joint space.19
Optimal-sized homogeneous colloid particles are small enough for engulfment by macrophages, but large enough to remain in the joint space.19

FIGURE 3 Optimal-sized homogeneous colloid particles are small enough for engulfment by macrophages, but large enough to remain in the joint space.19

Radiosynoviorthesis (the restoration of the synovium using a radioisotope) is a well-established human procedure, having been used around the world for >60 years, and is associated with a low adverse event rate (≈0.013%).11 Arthritic joints, which contain proinflammatory macrophages recruited during synovial hyperplasia, engulf colloid-embedded tin-117m microparticles, the active agent in Synovetin OA, and transport this complex to areas of synovial inflammation. Thereafter, tin-117m conversion electrons destroy the engorged macrophages responsible for inflammation via the noninflammatory process of apoptosis. This results in the synovium more closely reflecting the preinflammatory state and retards nociceptive transduction (pain). After decay, residual microparticles of inert tin are cleared via the lymphatic system to the liver.

Synovetin OA can be injected as an outpatient procedure. It is available from licensed specialty treatment centers, which can be located at Synovetin.com. For full prescribing information for Synovetin OA®, visit synovetin.com/package_insert.

 

For full prescribing information for Synovetin OA®, visit synovetin.com/package_insert.

References

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Digital Edition may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.


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Stelfonta CB AprilMay 2021

The Gentling Effect on Cats

Meghan E. Herron, DVM, DACVB, Gigi’s Shelter for Dogs, Canal Winchester, Ohio

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The Gentling Effect on Cats

In the Literature

Liu S, Paterson M, Camarri S, Murray L, Phillips CJC. The effects of the frequency and method of gentling on the behavior of cats in shelters. J Vet Behav. 2020;39:47-56.


FROM THE PAGE …

Cats often show signs of stress when away from the home. Stress-reduction techniques have been evaluated in both hospitalized and shelter cat populations. Practical means of reducing stress are needed to promote positive welfare, accelerate healing, and, in the case of shelter cats, improve adoption appeal. Gentling has historically been used to describe a combination of friendly interactions between humans and animals and may include long body strokes, brief head patting, soft speaking, and resting a hand on the animal. 

This study investigated how specific aspects and durations of gentling affected behavior in cats. Two experiments focused on the behavior of cats housed in a shelter in Queensland, Australia. In the first experiment, 60 cats were exposed to single-direction, head-to-tail petting for three 2-minute sessions per day, one 6-minute session per day, or no sessions. Cats were further divided into groups that experienced soft, friendly speaking delivered during the petting session or no vocalizations. The second experiment included 15 cats and more closely examined the duration of petting to determine whether 3-, 6-, or 9-minute sessions once daily for 4 days resulted in greater changes in behavior.

Results showed that a quiet petting session of 6 minutes once daily led to cats being near the front of their cage, being on the floor (rather than on a perch), and showing less pawing at the walls. Cats exposed to one 6- or 9-minute daily session showed an increase in purring, eating, and drinking. Soft speaking during the gentling sessions appeared to negate these positive effects.

Positive effects were noted only in the presence of the handler conducting the petting sessions. Cats did not remain on the floor or near the front of the cage when a stranger approached to pet them, suggesting familiarity plays a major role in cat comfort.


… TO YOUR PATIENTS

Key pearls to put into practice:

1

Although gentling may not dramatically alter behaviors of shelter cats, there is potential to improve cat’s overall welfare and, therefore, overall health and well-being.

2

Hospitalized and boarded cats may benefit from a single 6- to 9-minute session of gentle petting per day, particularly if consistency of handlers is possible. When handling cats, keeping quiet appears to be more beneficial than using soft vocalizations.

3

Providing gentle handling and extended, purposeful interactions with cats may benefit patient welfare during hospitalization or boarding. This, in turn, may help cats engage in normal, healthy behaviors (eg, eating, drinking) and return to health more quickly.

Suggested Reading

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Digital Edition may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.


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Arthrex CB AprilMay 2021

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Redonyl CB AprilMay 2021

Survival of Dogs with Primary Lung Tumors

Christopher B. Thomson, DVM, DACVS (SA), Veterinary Specialty Hospital of North County, San Marcos, California

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Survival of Dogs with Primary Lung Tumors

In the Literature

Rose RJ, Worley DR. A contemporary retrospective study of survival in dogs with primary lung tumors: 40 cases (2005-2017). Front Vet Sci. 2020;7:519703.


FROM THE PAGE …

The prognosis for dogs diagnosed with primary pulmonary tumors depends on multiple factors, including clinical signs, tumor-specific factors (eg, size, histologic subtype, grade), and clinical stage.1-4 Metastasis often occurs through the lymphatics because most lung tumors are derived from epithelial tissue; however, vascular and intra-airway spread has also been reported.2,4 Historically, lymph node metastasis has been highly associated with a significantly shorter survival,1-4 often prompting costly adjunctive treatment that may result in morbidity. Previous reports have suggested a survival of only 26 to 131 days in dogs with lymph node metastasis.1-3,5

In this contemporary retrospective study, records from 98 dogs that underwent surgery for a primary lung tumor were reviewed. Of these, 40 dogs with lymph node biopsy were also included. As this was a retrospective study, adjuvant treatments were not controlled. Multiple forms of maximally tolerated dose chemotherapy, metronomic chemotherapy, and other drugs were administered.

Of the dogs that underwent lymph node biopsy, 11 (27.5%) had metastasis to the lymph node. In univariate and multivariate analysis, presence of lymph node metastasis, administration of adjuvant chemotherapy, and mitotic index did not reach statistical significance. However, these data should be interpreted with caution due to the retrospective nature of the study and low numbers of cases in several categories. Similar to previous reports, the size of the primary tumor was negatively associated with survival; patients with a larger tumor had a significantly shorter survival time. 

Lymph node metastasis was identified via surgical histopathology in some dogs that had radiologically normal lymph nodes per CT imaging. This highlights the importance of surgical lymph node extirpation when possible, despite anatomy being occasionally challenging and regardless of the preoperative imaging findings. Additional research regarding the long-term impact of lymph node metastasis in dogs with primary lung tumors is warranted.

Dorsal reformatting of a contrast-enhanced CT scan in the soft tissue of a patient with a primary lung tumor. A large (&gt;6 cm in diameter) primary lung carcinoma (arrows) causing lateral deviation of the mainstem bronchi can be seen.
Dorsal reformatting of a contrast-enhanced CT scan in the soft tissue of a patient with a primary lung tumor. A large (&gt;6 cm in diameter) primary lung carcinoma (arrows) causing lateral deviation of the mainstem bronchi can be seen.

FIGURE 1 Dorsal reformatting of a contrast-enhanced CT scan in the soft tissue of a patient with a primary lung tumor. A large (>6 cm in diameter) primary lung carcinoma (arrows) causing lateral deviation of the mainstem bronchi can be seen.

FIGURE 1 Dorsal reformatting of a contrast-enhanced CT scan in the soft tissue of a patient with a primary lung tumor. A large (>6 cm in diameter) primary lung carcinoma (arrows) causing lateral deviation of the mainstem bronchi can be seen.

Sagittal reconstruction of a CT scan (from the same patient in Figure 1) that demonstrates an enlarged tracheobronchial lymph node (arrowheads)
Sagittal reconstruction of a CT scan (from the same patient in Figure 1) that demonstrates an enlarged tracheobronchial lymph node (arrowheads)

FIGURE 2 Sagittal reconstruction of a CT scan (from the same patient in Figure 1) that demonstrates an enlarged tracheobronchial lymph node (arrowheads)

FIGURE 2 Sagittal reconstruction of a CT scan (from the same patient in Figure 1) that demonstrates an enlarged tracheobronchial lymph node (arrowheads)


… TO YOUR PATIENTS

Key pearls to put into practice:

1

Survival of dogs with primary lung tumors can be prolonged with surgery alone; median survival was 167 days in dogs with lymph node metastasis and 456 days in dogs without metastasis.

2

The size of the primary lung tumor significantly impacts survival; patients with smaller tumors have a prolonged median survival time.

 

3

Lymph node extirpation should be performed during surgery when possible, despite the occasional challenges with anatomy and regardless of the preoperative imaging findings.

References

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Digital Edition may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.


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Algorithm CB AprilMay 2021

Prednisolone in the Development of Diabetes Mellitus in Cats

JD Foster, VMD, DACVIM, Friendship Hospital for Animals, Washington, DC

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Prednisolone in the Development of Diabetes Mellitus in Cats

In the Literature

Nerhagen S, Moberg HL, Boge GS, Glanemann B. Prednisolone-induced diabetes mellitus in the cat: a historical cohort. J Feline Med Surg. 2021;23(2):175-180.


FROM THE PAGE…

Most cats that develop diabetes mellitus (DM) are classified as having type 2 diabetes, which is caused by relatively impaired insulin secretion and insulin resistance.1 Uncommonly, cats can develop DM secondary to hypercortisolemia, hypersomatotropism, or autoimmune destruction of the endocrine pancreas. Therefore, it is prudent to evaluate for the cause of insulin resistance in most cats with DM. Physical inactivity, previous steroid administration, male sex, and consumption of dry food have been shown to be risk factors for the development of DM.2,3 However, the risk associated with prednisolone therapy on the development of DM is poorly described in the literature.

This retrospective study evaluated cats given prednisolone (≥1.9 mg/kg/day) for at least 3 weeks. The cats were monitored for at least 3 months after initial therapy. Of the 143 cats evaluated, 9.8% developed DM; most (85.7%) developed DM within the first 3 months of prednisolone therapy. No risk factors were observed to be associated with the development of DM in these cats; obesity and sex were not associated with increased risk. Although no significant difference was found among cats that did not develop DM, the median prednisolone dosage was higher in cats that did develop DM (3.5 mg/kg/day vs 2.9 mg/kg/day). This might be due to the small sample size of diabetic cats. In humans, steroid dosage is a risk factor for development of secondary DM4; larger studies in cats are required to evaluate this further. Lower dosages of prednisolone (≈5 mg/cat/day [NOT mg/kg]) are commonly used to treat inflammatory diseases (eg, inflammatory bowel disease, asthma). Anecdotally, DM has been observed in these patients; however, formal evaluation has not been done for lower dose or prolonged steroid administration, and until this has been evaluated, cats receiving any dosage of steroids should be considered to have increased risk for developing DM. Pet owners should be educated to monitor for clinical signs suggestive of disease.


…TO YOUR PATIENTS

Key pearls to put into practice:

1

Steroid therapy may result in insulin resistance and DM in cats. Most (64.3%) cats that developed DM in this study required insulin therapy and/or reduction of the steroid dosage for management of DM.

2

Although DM can occur at any time, most cats developed DM within the first 3 months of prednisolone therapy. It is important to educate owners on how to monitor for polyuria, polydipsia, and polyphagia, so cats that develop DM can be identified. Unlike dogs, cats do not normally exhibit polyuria/polydipsia with corticosteroid therapy.

3

Tapering to the lowest effective steroid dosage as soon as possible may help reduce the risk for secondary DM; however, this requires further evaluation.

References

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Digital Edition may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.


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Advantage CB AprilMay 2021

Leptospirosis: The Essential Need for Testing

Natalie L. Marks, DVM, CVJ

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Leptospirosis: The Essential Need for Testing
Sponsored by Merck Animal Health 

This past year has unveiled many challenges around the world, but if it has highlighted anything in medicine, it is that zoonotic disease (ie, disease spread from animals to humans) is a major threat to the health of the human population. Veterinarians and public health officers are responsible for protecting their patients and clients and should focus on reducing this threat by using parasite preventives and vaccination strategies to protect dogs from diseases that may pose a threat to humans.

Leptospirosis is the most widespread zoonotic disease worldwide,1 and although vaccination with a quadrivalent vaccine is core to patient and family protection, a strong prevention strategy must also include detection of positive patients through testing. In one study, 10% of humans infected with leptospirosis were infected from contact with their pets.2 Although these canine infections may be due to a lack of appropriate vaccination, they also represent a subset of patients that are frequently being missed in the profession.

Many patients can be presented with noticeable clinical signs of acute illness such as fever, inappetence, and vomiting, but leptospirosis can also create a worrisome chronic carrier status in dogs characterized by subclinical urinary shedding.3

Many patients can be presented with noticeable clinical signs of acute illness such as fever, inappetence, and vomiting, but leptospirosis can also create a worrisome chronic carrier status in dogs characterized by subclinical urinary shedding.

This urination creates a reservoir of leptospires in the home environment, placing young children and family members at increased risk for transmission. Without proper testing and treatment, these leptospires may be shed for months in the urine of patients, creating a consistent risk for zoonosis in the environment.1

Thankfully, several testing options are now available, including reference laboratory PCR and microscopic agglutination testing, as well as the more recent point-of-care testing for in-clinic use. Because there are limitations to all tests in that none are 100% sensitive (ie, a negative test in an acutely ill patient does not always rule out disease),4 it is always important to consider the timeline for a patient’s onset of clinical signs and the accuracy of each test before it is performed and during interpretation.

References

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Digital Edition may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.


Feline Orthopedic Examination

Wanda J. Gordon-Evans, DVM, PhD, DACVS, DACVSMR, University of Minnesota

Orthopedics

|Peer Reviewed

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Feline Orthopedic Examination

Orthopedic disease is common in cats.1-4 The goal of an orthopedic examination is to identify the source of pain and/or lameness; however, this can be difficult in cats.

In dogs, limping is the most common complaint for musculoskeletal disease, and it is easy to ascertain that an orthopedic examination is needed. In cats, the most common presenting complaints for musculoskeletal disease are changes in attitude (eg, being fractious or less playful), poor grooming, urination or defecation outside of the litter box, or the pet owner’s sense of undiagnosed illness in the cat; musculoskeletal disease may also affect mobility and flexibility, contributing to these signs.2,5-7 Inability to induce cats to consistently walk as desired and difficulty differentiating pain from fear or anxiety-related behaviors can also be challenging. Despite these challenges, orthopedic examination is important for diagnosis and establishment of a treatment plan.

Some cats may require sedation or behavior-modifying drugs prior to presentation; anesthesia may be required for staff safety in extreme cases. Although commonly used medications (eg, gabapentin) might not impact examination except in subtle cases, significant sedation or anesthesia may be required if the patient has signs of pain (eg, arousal, increased heart and/or respiratory rate, elevated blood pressure, focal muscle tremors). Examination may also need to rely more heavily on observation of swelling and palpation of abnormalities.

Initially, it is important to observe posture, stance, and ambulation.2 Most cats are not trained to walk on a leash, so the patient may need to be coaxed to walk. Observation of other behaviors may also help localize the problem. For example, cats with hip or back pain may be less willing to jump up on a chair or may attempt to jump and miss, or cats may stand on their pelvic limbs but keep their hips flexed and fully extend their hocks.

During examination, musculature should be palpated for symmetry.2 Muscle atrophy, masses, and/or swelling can provide direction to a specific limb (especially if observation of ambulation was not successful). Cats that tolerate examination can have unaffected limbs examined first, allowing observation of normal reactivity; this can help in detection of subtle reactions attributable to pain.7 However, most cats only tolerate examination for a short period of time, so beginning with the unaffected limbs may not be prudent in all cases.

It is important to start at the distal aspect of the limbs and work proximally. Constant contact should be used, starting from the torso to the digits, as this can be less aversive than just reaching for the digits. Cats are less stressed and may be more cooperative when in a comfortable location or position (eg, reclining, standing, being held by the owner). Cats that fold the limbs under the body can have the chest or pelvis supported while the thoracic or pelvic limbs, respectively, are examined (Figure 1).

When examining a joint, spreading pressure over a wide area with multiple fingers or a palm can decrease the effect of pressure on bones and soft tissues, isolating the joint as the potential source of pain. Otherwise, very focal pressure may cause pain at the gripping point, which can confound assessment of joint pain. Normal range of motion and locations for palpating swelling are presented in the Table.

Cat with elbow flexion. The chest is supported, the elbow is flexed, and the shoulder is maintained in a neutral position.&nbsp;
Cat with elbow flexion. The chest is supported, the elbow is flexed, and the shoulder is maintained in a neutral position.&nbsp;

Figure 1 Cat with elbow flexion. The chest is supported, the elbow is flexed, and the shoulder is maintained in a neutral position. 

Figure 1 Cat with elbow flexion. The chest is supported, the elbow is flexed, and the shoulder is maintained in a neutral position. 

Assessment of the Shoulder, Hip, & Lumbar Region

Shoulders and hips cannot be palpated for effusion because of muscle coverage, and difficulty with isolation can make assessment challenging. For example, when the hips and shoulders are extended, the stifle and elbow are also extended, respectively, and the hips or shoulders are no longer isolated (Figure 2). This may make pain isolation especially difficult in the pelvic limbs when assessing for hip dysplasia, as the hips may not be the only source of pain.8 As the hips are extended, the lumbosacral aspect of the back is also extended, and a pain response may be solely or partially attributed to osteoarthritis in the lumbar spine.

Back and hip pain can be differentiated using a combination of multiple aspects. For example, cats with lumbar pain typically do not have pain on flexion or abduction of the hip but do have pain on direct palpation of the back or extension of the pelvis with the hips in neutral or flexed position. Conversely, pain attributed to the hip may be present when the hip is abducted, but this movement will not impact other joints or the back. Similarly, in the forelimb, if the scapula is fixed in position, the humerus can be abducted to an ≈45-degree angle. This movement does not affect the distal joints, unlike extension of the shoulder. The abduction angle should be symmetrical with the opposite side, and excessive abduction may indicate collateral ligament damage.

Cat with hip extension. Simultaneous extension of the hock and stifle can be seen.
Cat with hip extension. Simultaneous extension of the hock and stifle can be seen.

Figure 2 Cat with hip extension. Simultaneous extension of the hock and stifle can be seen.

Figure 2 Cat with hip extension. Simultaneous extension of the hock and stifle can be seen.

Instability

Separate evaluation for instability should be performed in cats with swelling, history indications (eg, specific trauma), or unremarkable physical examination. Medial and lateral stress should be used to test instability of the collateral ligaments, except in the hip where collateral ligaments are not present. Palpating the unaffected side can be helpful in distinguishing normal from abnormal movement. The joint angle should be held constant while palpating for collateral ligament instability. Allowing flexion or extension while palpating for varus and valgus instability can make detection of abnormalities difficult; this is easiest in a neutral joint angle. However, the hock may be tested separately in both flexion and extension to determine which ligament is more specifically affected and to ascertain subtle abnormalities. The talofibular ligament is the primary stabilizer in flexion, but the long and short collateral ligaments stabilize extension. Dorsal or palmar/plantar ligament abnormalities can also be detected by stabilizing the tibia or radius and placing pressure on the metacarpals or metatarsals both cranially and caudally.

Table

NORMAL LANDMARKS FOR EFFUSION & RANGE OF MOTION

Joint Flexion Landmarks Extension Landmarks Joint Effusion
Phalanges Digital and metacarpal or metatarsal pads touch Normal standing position; claws should be extendable Externally palpable dorsally
Carpus Paw pads touch the antebrachium Normal standing position just past 180 degrees Palpated over the dorsal carpal surface of the small carpal bones when palpated in slight flexion
Elbow Carpus touches the shoulder Straight limb from shoulder to carpus Palpated by finding the lateral epicondyle and palpating caudally toward the ulna
Shoulder Elbow travels lateral to the fourth rib toward the ventral aspect of the scapula Limb points out past the head, almost parallel to the line of the spine Not palpable
Hock When stifle is allowed to flex, the dorsal metatarsals touch the tibia. The hock will only flex slightly if the stifle is not allowed to flex when the hock is flexed (tibial compression test). Straight limb from tibia to metatarsals The transition of bone palpated from the medial and lateral malleolus caudally to the calcaneus
Stifle Tuber calcaneus touches the ischiatic tuber Limb is straight from femur to tibia when visualizing from the lateral direction Palpated by feeling both sides of the patellar ligament
Hip Stifle touches the ventral ilium Femur extends caudally, almost parallel with the spine Not palpable
Cervical spine Head touches the chest and both left and right shoulders Head manipulated, with the nose pointed dorsally Not palpable
Thoracolumbar spine Knees touch elbows to determine spinal flexion from lateral direction Straight spine or slight ventral curve Not palpable

Cruciate & Patellar Disease

Although cats are not predisposed to cranial cruciate ligament rupture or patellar luxation, occasional prevalence necessitates careful evaluation. A cranial cruciate ligament rupture can be detected using the tibial compression test or the cranial drawer test. Presence of patellar luxation can be detected by applying gentle pressure medially and laterally to determine whether the patella luxates during range of motion; this is easiest in stifle extension and can be performed in flexion in some instances. Cats generally have more patellar movement medially and laterally than dogs; however, the patella rebounds to the correct position when not being held.

Tibial compression test is positive if the tibial tuberosity moves forward in relation to the femoral condyles when the hock is flexed. The cranial drawer test can be used to determine cranial cruciate ligament rupture (ie, cranial drawer) or caudal cruciate ligament rupture (ie, caudal drawer). To determine whether reactions were coincidental (ie, attributable to restraint) or attributable to pain, these procedures may need to be repeated, depending on the severity of pain and clinical confidence in the results.


Step-by-Step

FELINE ORTHOPEDIC EXAMINATION

STEP 1

Coax the cat to walk around the examination room. Observe the cat’s locomotion and posture to evaluate for the presence of limping, abnormal gait, weight shifting, mechanical abnormalities (eg, dropped hocks), and/or neurologic disease (eg, lameness, weakness, ataxia). Observe for other clinical behaviors that may assist in lesion localization. 

Clinician's Brief

Author Insight

The cat can be filmed at home or in the examination room to help in evaluation of locomotion. Viewing the film in slow motion can help in detection of important nuances in movement that might be overlooked when viewed at normal speed.


STEP 2

Palpate the musculature for symmetry, and look for muscle atrophy, masses, and/or swelling that can provide direction to a specific limb. If the cat is tolerating the examination well, examine the unaffected limbs first and observe subsequent behaviors.


STEP 3

Start at the distal aspect of the limbs and work proximally. Begin with the digits, and inspect the nails (use gentle dorsal pressure on the digit to extend the nail) and the interdigital skin for injury, swelling, draining tracts, or redness. Flex and extend only the digits while isolating the joints distal to the metacarpophalangeal or metatarsophalangeal joints. If the cat resists, vocalizes, demonstrates aggression, or attempts escape with flexion of all the digits, then isolate, flex, and extend each individual digit in turn.

Clinician's Brief

STEP 4

As the examination proceeds proximally, palpate the bones, soft tissues, and joints for pain, swelling, or instability. Press on the distal bone and soft tissue using broad pressure to flex and extend the joints while ensuring the other joints are at a neutral angle.

Clinician's Brief
Clinician's Brief

Author Insight

Palpating the soft tissue and bone prior to assessing joint range of motion can help differentiate the source of the pain (eg, bone vs joint).


STEP 5

To isolate the lumbar spine for pain evaluation, with the cat in lateral recumbency, palpate the small divot palpable on the dorsal midline caudal to the L7 dorsal spinous process between the ilial wings or the lumbosacral area (A), and press the feet proximally to flex the hips and extend the lumbar spine (B).

Clinician's Brief
Clinician's Brief

STEP 6

If a special examination for instability is indicated, use medial and lateral stress to test instability of the joint’s collateral ligaments for all joints distal to the shoulder or hip. When examining the hindlimb, place the hands proximal and distal to the hock. Stress the medial collateral ligament by introducing pressure up (solid arrows), and stress the lateral collateral ligament by introducing pressure down (dashed arrows). Do not allow the patient to move while in flexion or extension and while the collateral ligaments are being stressed. 

Clinician's Brief

STEP 7

For suspected cranial cruciate ligament rupture, conduct a tibial compression test or a cranial drawer test. During the tibial compression test, prevent the stifle from flexing as the hock is flexed (A). Rest the index finger on the tibial tuberosity to palpate for cranial movement. Perform the cranial drawer test by placing the thumb of the proximal hand on the lateral fabella and the index finger on the patella (B), then place the thumb of the distal hand on the fibular head and the index finger on the tibial tuberosity, and hold the femur in place while moving the tibia cranially or caudally.

Clinician's Brief
Clinician's Brief

References

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Digital Edition may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.


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Seresto CB AprilMay 2021

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Mirataz CB April/May 2021

Sudden Onset of Fear & Panic in a Bernese Mountain Dog

Amy L. Pike, DVM, DACVB, Animal Behavior Wellness Center, Fairfax, Virginia

Behavior

|Peer Reviewed|Web-Exclusive

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Sudden Onset of Fear & Panic in a Bernese Mountain Dog

Luna, a 9-month-old, 60-lb (27-kg) intact female Bernese mountain dog, had a sudden onset of severe fear and panic toward new elements in her environment, unfamiliar humans, and riding in a car after she fell from a moving vehicle at 4 months of age.

Prior to Luna falling out of the car, her owners reported that she was normal, quickly accepted unfamiliar humans, and appeared to enjoy riding in the car. After falling, Luna began to startle, back up, bark, and growl when encountering novel items (eg, a plastic bag blowing in the wind); pant, bark, growl, and attempt to hide when unfamiliar humans entered the home; and back up, cower, tremble, pant, and profusely drool when being lifted into and riding in the car. She also appeared fearful when walking underneath objects (eg, trees, entryways). These behaviors continued for the next 5 months, at which time she was presented to a behavior clinic. 

Physical Examination & Diagnostics

Luna was initially presented to an emergency veterinary clinic after the fall. Diagnostic evaluation (including CBC, serum chemistry profile, and urinalysis) was performed, and all results were within normal limits. Because there was possible head trauma from the fall, she was also referred to a neurologist where a brain MRI was completed—results were also within normal limits.

Physical and neurologic examination findings at the time of presentation to the behavior clinic were also within normal limits. Behavior signs in the examination room included panting, pinning her ears back, cowering near her owners, and being unwilling to interact with staff or take treats during the consultation; her pupils were also dilated (Figure). An FAS (ie, Fear, Anxiety, and Stress) spectrum and pain algorithm was used (see Suggested Reading), on which Luna scored an FAS 4: severe.

Luna with dilated pupils, panting, and pinned back ears; these signs persisted throughout the consultation.
Luna with dilated pupils, panting, and pinned back ears; these signs persisted throughout the consultation.

FIGURE Luna with dilated pupils, panting, and pinned back ears; these signs persisted throughout the consultation.

FIGURE Luna with dilated pupils, panting, and pinned back ears; these signs persisted throughout the consultation.

DIAGNOSIS:

CHRONIC POST-TRAUMATIC STRESS DISORDER

Based on patient history, and because the behavior issues were persistent and did not resolve, chronic post-traumatic stress disorder (PTSD) was diagnosed.

Secondary diagnoses included generalized anxiety disorder (based on the patient spending most of her time in an anxious state), global phobia (ie, persistent and excessive fears that are potentially irrational in nature), neophobia (ie, exaggerated fear response to novel items), and fear-based aggression (ie, distance increasing body postures and vocalizations [eg, barking, growling, snarling, lunging, nipping, snapping, biting] toward unfamiliar humans and dogs).

Treatment

Treatment for behavior issues should include environmental management, behavior modification, and medical therapy.

Environmental Management

Environmental management is important for elimination of unwanted behavior, as well as elimination (as much as feasible) of fear, anxiety, and frustration that are often the underlying cause of behavior concerns. Learning can only take place when the patient is not experiencing a high level of emotional arousal; thus, environmental management is the first step in treatment, before behavior modification can be started.

Luna’s owners were instructed to attempt to avoid triggering situations during the treatment period, including not having guests in the home, not driving Luna in the car, and taking Luna on walks during nonpeak hours. Her owners were told to remove her from triggering encounters as quickly as possible.

TREATMENT AT A GLANCE

  • Any possible medical etiology should be ruled out, especially in patients with a sudden change in behavior.
  • Strict environmental management should be implemented to avoid unwanted behavior and keep the patient under threshold during treatment.
  • Appropriate psychotropic medications and products should be considered to help reduce fear, anxiety, and stress.
  • Behavior modification, including DSCC, with the assistance of a board-certified veterinary behaviorist or other qualified positive-reinforcement–based trainer can be helpful.

Behavior Modification

Behavior modification involves either teaching an alternate incompatible behavior to replace the unwanted behavior or altering the emotional state from one that is negative to one that is positive or neutral (ie, desensitization and counterconditioning [DSCC]).

Initial behavior modification techniques were focused on additional management strategies, including teaching Luna to wear a basket muzzle and perform an emergency U-turn (ie, a 180-degree turn away from the trigger/stimulus). Further behavior modification was delayed until Luna’s anxiety was low enough to remain under threshold (ie, the level at which emotional arousal is too high and a negative reaction occurs). Once Luna’s anxiety was under control, DSCC for her triggers could begin (see Desensitization & Counterconditioning for a Trigger).

DESENSITIZATION & COUNTERCONDITIONING FOR A TRIGGER

To address Luna's fear of plastic bags, the distance at which she had no negative reaction toward the bag was determined. The bag was presented to her at that distance, her owner fed her a high-value reward, and the bag was removed when she stopped feeding. Once Luna developed a positive emotional response to the presence of the bag (as a result of receiving a high-value reward), criteria were increased, including bringing the bag closer to her or having the bag make noise or move. Luna was kept under threshold for reaction, and focus was kept on creating a positive emotional response before moving to next steps.

Medical Therapy

Environmental management alone is impractical, and complete compliance is difficult in patients with numerous triggers, as with Luna and most patients with this set of diagnoses. Anxiolytic medication is thus necessary. Medical therapy is often multimodal, targeting ≥1 neurotransmitters (NTs) involved in fear and anxiety and includes serotonin (ie, coping NT), dopamine (ie, pleasure/activation NT), γ-aminobutyric acid (ie, inhibitory NT), and norepinephrine (ie, NT involved in fight/flight modulation).

Treatment for dogs with chronic PTSD and other phobias can be challenging, and the correct medications and products are needed for behavior modification.

Luna was started on the following:

  • Sertraline (25 mg twice daily [≈1 mg/kg PO every 12 hours]), which was chosen because it is a selective serotonin reuptake inhibitor that targets serotonin and dopamine increases via inhibition of reuptake in the postsynaptic cleft.1 In humans, sertraline is approved for use in patients with PTSD and social phobias.2-4
  • Alprazolam (1-3 mg PO prior to or immediately after any panic-inducing situation [≈0.04-0.1 mg/kg PO every 6-8 hours as needed]), which is shown to be effective in treating dogs with noise phobia and often useful for treatment of other phobia disorders (eg, noise phobia)5,6
  • α-casozepine (450 mg; used as directed based on patient weight), which is used for calming effects in dogs with anxiety disorders7
  • Pheromone collar (used as directed by the manufacturer); maternal-appeasing pheromones have been shown to help dogs with noise phobias and other anxiety disorders (eg, travel anxiety).8-10

Nutraceuticals and pheromones may augment medical therapy and potentially improve outcomes when combined with other treatment modalities.11

After 4 weeks, sertraline was increased to 50 mg twice daily (≈2 mg/kg PO every 12 hours) based on an ≈60% reduction in intensity of fear and anxiety, as well as a continued need for improvement. All other drugs and products were continued at the starting dosages. Luna’s owners reported a decrease in the intensity of reactions to triggers and slightly decreased time of recovery, but attempts at DSCC were still unsuccessful. Management was still difficult due to the numerous triggers Luna experienced daily; this was partly due to living in an apartment complex in a major metropolitan area and the need to walk Luna for elimination purposes on a busy street. 

Prognosis & Outcome

Once Luna’s anxiety was lowered and she was able to be under threshold while at a reasonable distance from triggering situations, a program of DSCC to specific triggers (eg, riding in a car, meeting new people, going through thresholds and under trees) was implemented.

Despite moderate improvement in fear intensity and ability to recover when triggered, Luna’s owners chose to relinquish her because they lived in an urban area in which she was exposed to triggers daily and because they were first-time dog owners who felt overwhelmed by her continued need for behavioral care. Luna’s breeder assisted in rehoming her with a family in a suburban area in which management could be more easily accomplished. Luna had significant progress with the new family, presumably due to the combined effect of being in a new environment, ongoing medical therapy, and the new owner’s commitment to the prescribed behavior modification plan. Alprazolam was rarely needed; however, her owners continued sertraline and other products because of Luna’s progress and the owner’s hesitance for potential setbacks.

Discussion

Canine PTSD is diagnosed based on the patient experiencing a potentially traumatizing event and subsequently developing signs like hypervigilance, aggression, compulsive disorders, sleep disturbance, increased startle response, fear, avoidance, and/or withdrawal. These signs persist >1 month after the traumatic event and are not present prior to the event. Similar experiences in humans should be used as criteria when diagnosing PTSD. Prevalence of PTSD in dogs is widely unknown due to lack of retrospective studies.12

Sudden onset of behavior is usually an indicator that a thorough medical workup is needed. Once medical etiologies have been ruled out and diagnostic criteria for behavior disorders are met, treatment can be started to alleviate and modify signs.

TAKE-HOME MESSAGES

  • Medical etiologies should always be considered and ruled out when there is a sudden change in behavior.
  • Traumatic events can cause PTSD in companion animals similar to that seen in humans.12
  • Treatment for PTSD and other behavior problems should include a 3-part approach (ie, environmental management, behavior modification, medical therapy).
  • Behavior modification, which is key for behavior disorders, cannot proceed until triggers do not immediately push the patient over their threshold.
  • Psychotropic medications and products can positively impact patient well-being.
  • Some owners may be unable or unwilling to care for a patient with behavior disorders.
  • Improved living environment can impact treatment outcomes.

References

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Digital Edition may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.


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Rough Anesthetic Recoveries

Renata S. Costa, DVM, MPhil, MANZCVS, GradDipEd, DACVAA, Midwestern University, Glendale, Arizona

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Rough Anesthetic Recoveries

Anesthetic recovery is a critical part of the anesthesia process.1-3 During the recovery period, the effects of anesthetic agents may still be present, and the patient may not have regained full consciousness and can react abruptly and unexpectedly. Therefore, the postanesthetic period requires attentive monitoring. It is also imperative that an appropriate perioperative plan be developed to minimize the risk for a rough recovery and/or to allow for timely intervention before patients accidently cause injury to themselves or those around them. 

Patient- and anesthesia-related factors can cause a rough recovery, and understanding common contributing factors can help determine the most likely diagnosis and best treatment plan.* Although it can be difficult to differentiate pain from other behaviors (eg, anxiety, stress, dysphoria)—as many of the physiologic responses are similar4-7—assessment of behavior prior to administering any agents, use of multidimensional pain scales, and knowledge of drug effects and duration of action can help facilitate correct interpretation of behaviors displayed in the postanesthetic period.

The common causes of rough recoveries in dogs and cats discussed in this article are emergence delirium, pain, anxiety, bladder distension, opioid dysphoria, and benzodiazepine disinhibition.4-6,8,9 Clinical signs are often similar regardless of the actual cause. Therefore, methodical assessment of the patient, as well as knowledge of when clinical signs started, drugs were administered, and patient pain level can help identify the most likely etiology of the rough recovery (see Rough Recovery Guidelines).

ROUGH RECOVERY GUIDELINES

Fast action is crucial if recovery is rough and may cause harm. However, if there is time, the patient should be assessed and the cause of the rough recovery identified prior to administration of any medication. Following are some treatment options for common causes of rough recovery.

Emergence Delirium

  • Small dose of induction agent
  • Propofol (0.5-1 mg/kg slow IV; cats and dogs)
    • Stopped when clinical signs subside

Pain

It should be determined how painful the procedure was and whether the patient needs additional analgesia (based on patient response), as well as when the last dose of analgesic was given and the drug’s duration of action. Not all patients with rough recovery that vocalize are painful. A pain scale should be used to determine a pain score, as pain assessment can help determine whether analgesia is needed.

  • Analgesics (ie, opioids, NSAIDs) are needed with a high pain score or when the patient is being assessed and it is not clear whether the patient is in pain.

Anxiety, Fear, & Aggression

Based on assessment of the patient’s temperament prior to anesthesia, extra sedation may be needed. If this is the case, one of the following drugs (if there are no contraindications) can be administered and the patient reassessed:

  • Low-dose acepromazine (0.01 mg/kg IV; cats and dogs)
  • Low-dose dexmedetomidine (0.001 mg/kg IV; cats and dogs) 

Bladder Distension

The bladder should be expressed or the patient walked if possible.

Opioid Dysphoria

  • Butorphanol (0.1 mg/kg IV or IM; cats and dogs)
  • Naloxone (0.005-0.01 mg/kg slow IV; cats and dogs), diluted prior to administration. The usual concentration is 0.4 mg/mL, which should be diluted to obtain a new concentration of 0.04 mg/mL (eg, 1 mL of undiluted naloxone and 9 mL of saline). Recommended rate of administration of the dilution is 0.5-1 mL/40 seconds. Administration should be stopped when clinical signs subside.
    • Naloxone administered too fast or at a dose that is too large can reverse analgesia and cause the patient to become painful. A rescue analgesic protocol should be prepared ahead of time.
    • Careful monitoring is needed, and readministration may be warranted if signs return.

Benzodiazepine (ie, Midazolam/Diazepam) Disinhibition

  • Flumazenil (0.01 mg/kg slow IV; cats and dogs)
    • Stopped when clinical signs subside 

Emergence Delirium

Emergence delirium is a state of mental confusion and psychomotor agitation marked by hyperexcitability, restlessness, uncontrolled thrashing, and vocalization. Patients do not interact with humans and are unaware of their environment.7,10 Signs are abrupt and usually occur following rapid emergence from anesthesia when the patient has not yet regained complete consciousness. The etiology is unclear, but early anesthesia arousal following use of short-acting inhalation anesthetics may be a contributing factor.6,10,11

Timing of clinical signs can help differentiate emergence delirium from other causes of a rough recovery. Emergence delirium occurs in the immediate recovery period, typically soon after inhalant anesthesia is discontinued. Patients may thrash uncontrollably and require rapid intervention to prevent injury. Administration of a small dose of an induction agent such as propofol (0.5-1 mg/kg slow IV; cats and dogs) is recommended.7 Propofol is commonly used due to its fast onset and short duration of action but should be administered slowly until clinical signs subside. Excessive and fast administration should be avoided to reduce the risk for apnea and hypotension due to vasodilation.

Pain

Clinical signs of pain include vocalization, restlessness, hyperventilation or panting, and aggression, especially when painful areas are touched.12,13

Pain can be diagnosed using a pain scale (eg, short-form Glasgow Composite Measure Pain Scale, Colorado State University Acute Pain Scale).12,14 Knowledge of the analgesic protocol used, duration of action, and time of administration can also help reach a diagnosis. An analgesic trial with opioids (eg, methadone or hydromorphone [0.1 mg/kg IV], buprenorphine [0.02 mg/kg IV]; cats and dogs) or other analgesic agents (eg, ketamine [0.6 mg/kg/hour CRI; cats and dogs]; NSAIDs) should be instituted and the patient reassessed if there is uncertainty on whether the patient is still painful.

Anxiety, Fear, & Aggression

Anxiety is the uncertainty and fear that result from anticipation of a real or imaginary threat and often impairs physical and psychological functioning. Clinical signs include vocalization, panting, and restlessness.15

Patients in which adequate pain management has been implemented but persistent vocalization and restlessness continues may be experiencing fear, stress, and/or anxiety. Administration of a tranquilizer or sedative (eg, acepromazine [0.01 mg/kg IV], dexmedetomidine [0.001 mg/kg IV]; cats and dogs) can be considered if there are no contraindications (eg, previous allergic reaction to the agent, patient is hypovolemic)4,7; however, some dogs and cats may only have a temporary response. In these cases, especially if restlessness is due to anxiety, agents such as trazodone (3-10 mg/kg PO) or gabapentin (10-25 mg/kg PO) can be administered. The patient will need to be reassessed after initial treatment, as some patients may require higher doses of these agents. The aim, however, should be to administer the lowest dose possible to minimize the risk for adverse effects while still achieving the desired outcome. Trazodone enhances calmness, reduces anxiety, and produces mild sedation with no apparent relevant adverse effects in dogs.16,17

Patients that are anxious may respond to being held, but this is not always feasible. Nonpharmacologic alternatives include anxiety or pressure wraps (eg, a thunder jacket) that maintain swaddling pressure and acupressure aimed to induce calmness.18,19

Bladder Distension

Bladder-distension–related discomfort may result in vocalization, restlessness, tachycardia, and/or panting.4,5,20 The bladder should be palpated and expressed prior to recovery.

During the postanesthetic period, if there are signs of discomfort and restlessness, bladder size and turgidity should be reassessed and the bladder gently expressed if it is distended—this may minimize discomfort.5 Ambulatory patients should be walked.

Opioid Dysphoria

Opioids, especially µ agonists (eg, hydromorphone, fentanyl), can result in dysphoric recoveries marked by vocalization, restlessness, hyperthermia, panting, and/or lack of response to human contact.4,8 Opioid-related dysphoria is often a diagnosis of exclusion made after pain and bladder distension are ruled out and in patients with no response following administration of sedatives and tranquilizers. In these cases, µ-agonist–opioid administration worsens clinical signs. This highlights the importance of accurate pain assessment prior to administering these agents.

Butorphanol is a κ-agonist, µ-antagonist opioid that can reverse the adverse effects of µ-agonist opioids21 and provide mild analgesia. Naloxone is the actual reversal agent and results in rapid resolution of adverse effects10,21; however, this drug has the potential to reverse the analgesic properties of the opioid. To decrease the risk for reversing analgesia, naloxone (0.005-0.01 mg/kg; cats and dogs) should be diluted (see Rough Recovery Guidelines) to allow for slow IV administration (0.5-1 mL/40 seconds) and stopped when signs subside. A rescue analgesic protocol should always be prepared ahead of time, and the patient should be pain scored. Clinical signs that stop after reversal confirms the diagnosis of opioid dysphoria.

Benzodiazepine Disinhibition

Benzodiazepine disinhibition is a paradoxical response that follows administration of these sedatives (eg, diazepam, midazolam); this reaction is often observed in healthy dogs and cats. Signs may be seen immediately after administration and/or during the recovery period and include vocalization, hyperexcitability, ataxia, drooling, nystagmus, aggression, and sudden attempts to eat the fluid line and bandages.22,23 A higher incidence of disinhibition occurs in healthy patients but the etiology is not completely understood.24,25

Benzodiazepine disinhibition is often a diagnosis of exclusion that is made when the patient fails to respond to analgesics, sedatives, and tranquilizers. Flumazenil (0.01 mg/kg slow IV; cats and dogs) is the reversal agent and results in rapid cessation of clinical signs,25,26 confirming the diagnosis of benzodiazepine disinhibition.

Prognosis & Prevention

Reviewing patient history and medical records of previous sedation and anesthetic recoveries before medication is administered can help prevent a rough recovery. It is also important to properly record any rough recovery, treatment provided, and responses to treatment. Knowledge of previously noted complications can help clinicians anticipate potential future issues and implement pre-emptive strategies. Strategies may include modification of the anesthetic protocol and administration of preanesthetic drugs at home27 and/or in the clinic. For example, a cat that previously experienced benzodiazepine-induced disinhibition on recovery should receive a different premedication protocol, or a dog with a known history of opioid-related dysphoria can often be managed with opioid-minimal/opioid-free protocols, emphasizing locoregional analgesia, NSAIDs, and CRIs of nonopioid drugs (eg, lidocaine, dexmedetomidine, ketamine). Consultation with a board-certified specialist in veterinary anesthesia and analgesia can be helpful in these cases.

Using a pain scoring scale prior to starting the procedure and prior to drug administration can help during the recovery period—for example, this can aid in differentiating whether vocalization is due to pain or anxiety. An adequate analgesic protocol is also a key component for optimal perioperative management and return to normal physiologic function. Some agents may need to be readministered depending on the procedure, patient response, type of analgesic used, time of drug administration, and duration of action of each drug. Suboptimal use of analgesics, but also unnecessary administration of drugs (eg, opioids) to nonpainful patients, can result in a rough recovery. 

Conclusion

To correctly diagnose a rough anesthetic recovery, it is important to anticipate and reduce pain, anxiety, and fear (using pharmacologic and/or nonpharmacologic methods), as well as to understand the temperament of the patient, procedure, medications, and possible drug interactions. Knowledge of common causes of rough recoveries and appropriate treatment can aid in optimization of the recovery period.

*Drug dosages in this article are suggestions. Individual patients should be assessed to establish whether lower or higher doses are required based on adverse effects and patient status. Adequacy of the chosen drug should also be determined.

References

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Digital Edition may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.


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