The dermatological signs of food allergy in dogs and cats are indistinguishable from those of environmental allergies, with itching being the most common presentation. Food allergy can also cause gastrointestinal issues, such as flatulence, frequent defecation, vomiting or diarrhea. When those signs are combined with dermatitis, there is a greater suggestion of food allergy. No treatment for food allergy will work better than simply removing the offending protein or two from the diet entirely. And the only way to know what to remove, is by doing an excellent diet trial. That’s right, there is no good way to allergy test for food allergies, other than good, old fashion, trial and error. Luckily, we are here to help!
Food allergy explaining all clinical signs of dermatitis accounts for about 10% of dogs and cats with allergic dermatitis. There is approximately another 20% that will achieve partial improvement on an elimination diet. These percentages are thought to be slightly higher if the patient is younger than 6 months of age or older than 12 months of age. Most patients diagnosed with food allergy have been eating the offending protein for 2 years or longer.
Of the patients that improve significantly on an elimination diet trial, about 50% take a month before seeing improvement, the other half takes 8 weeks or longer. That is why we do such long diet trials.
It may surprise you to learn that grains are rarely responsible for food allergy in dogs and cats. The offending protein is usually the meat, poultry or fish source that the pet has been eating predominantly for long periods. To my knowledge, there is no evidence to support grains as common food allergens. Nor is there conclusive evidence of grain free diets being advantageous to dogs in general. On the contrary, there is some early evidence linking them to certain kinds of heart disease in dogs.
To choose the diet trial that is right for your pet, we review all previous food ingredients and ideally, find a diet with one protein and one starch that your pet has never eaten before. This can be a home-cooked meal, but most folks prefer a prepared diet, so I usually use prescription diets with very limited ingredients and the most reliable production consistency. Over the counter brands tend to be a bit more variable, so they are sometimes fine for maintenance, but I try not to count on them during the crucial testing period.
Watch for our next blog, “Diet Trials to Diagnose Food Allergy in Pets”, and let us know when you are ready to find out, once and for all, if your pet has a food allergy. We can help!