Dr. Jeromin: I tend to see food allergies most commonly in young dogs. Otitis externa is commonly seen with adverse food reactions, so ear infections are a common sign.2 These dogs are generally pruritic or erythematous, which can result in pyodermas or recurrent yeast infections. The literature says 38% of food-allergic dogs start showing clinical signs before 1 year of age, but food allergies can start at any age.2,3 When I get a patient with GI signs or a history of GI issues with skin signs, the lightbulb kind of goes off for me; we’re going to consider food allergies, especially if clinical signs are nonseasonal. As for cats, they run their own show. Anything can look like food allergies in a cat—miliary dermatitis, eosinophilic granuloma. I’m not going to jump to psychogenic alopecia right away; I’m going to try to investigate the underlying cause. Is it food allergy and we didn’t do a proper elimination diet trial? The literature says the mean age of onset of clinical signs in cats is 4 to 5 years.1,4 Cats always like to do things a little differently.
Dr. Rudinsky: As far as presentations to the internal medicine service, I normally see patients with diarrhea, vomiting, and weight loss, which are classic GI signs. Once they have any sort of concurrent dermatologic sign, that’s going to raise my concern for food allergy immensely and change how I approach them therapeutically, dietarily, and otherwise. I really emphasize that the dermatologic component can vary—from recurrent ear problems to other classic signs of atopic dermatitis.
Dr. Raditic: It’s wonderful to hear from a dermatologist and an internist. I get patients referred to me from both of those services and also often straight from the general practitioner, often presenting with both dermatologic and gastrointestinal signs. I try to explain that the gut is a tube on the inside, and the skin’s the tube on the outside, so both can be involved in food allergy, and food plays a huge role in the health and well-being of the immune system, as well as the lining of the gut and skin.
Dr. Jeromin: Sometimes on initial presentation, you have an owner who has already diagnosed presumed food allergies in their pet. How many times do you hear, “Oh, I took him off all beef!”? I’d rather have a client who hasn’t done any reading about it or spent $300 on an unreliable IgE serum test for food so I don’t have to break all that down, because once they get that in their head and they get that paper that says what that dog or cat’s allergic to, it’s hard to say, “Sorry, I’m the bad guy here, but all that work you did it, it’s not true.”
Dr. Rudinsky: Especially on the GI side of things. Owners will give their dog half a rotisserie chicken as a treat, and at the end of the day, the dog has a relapse in its GI signs and they want to call it a chicken allergy. Then, all of a sudden, they don’t want to feed anything with chicken in it, which may or may not actually be the problem. We need to start from a clean slate and break down all that information they’re finding online, so much of which is misinformation. People are just inundated with this misinformation, and we’re often behind the starting line.
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