Food allergy is one of the causes of itching in dogs and cats, though a clearly less common cause than environmental allergy (atopy). Many owners believe grains are the problem, but research clearly shows: the most common allergens are animal proteins — beef (34%), dairy (17%) and chicken (15%). A correct diagnosis requires an elimination diet, and we can help you with that.
Symptoms
The most common symptoms of food allergy are itching, recurring ear infections, paw licking, skin infections and gastrointestinal symptoms (vomiting, diarrhea). In cats, symptoms often appear as itching around the head and neck. Unlike environmental allergies, food allergy is not seasonal — symptoms persist year-round. If your pet has more than 2 bowel movements per day and skin symptoms started before one year of age, food allergy is particularly likely.
Most Common Allergens
In studies, the most common allergens in dogs are beef (34%), dairy (17%), chicken (15%), wheat (13%) and soy (6%). In cats, the most common are beef (18%), fish (17%) and chicken (5%). Grains cause only a small portion of allergy cases — wheat 13% and corn 4%. "Grain-free" food is not the solution because it often still contains the most common allergens (beef, chicken). Additionally, replacing grains with legumes has been linked to heart disease (DCM) risk in dogs.
Elimination Diet — The Only Reliable Diagnostic Method
Allergy blood tests for food are not reliable — in one study, all 30 healthy dogs with no allergy history received false positive results. The only reliable method is an elimination diet: the pet is fed for 8–12 weeks exclusively hydrolyzed protein food where proteins have been broken down so small that the immune system cannot recognize them.
Elimination Diet Rules
The elimination diet must be absolutely strict. ONLY the elimination food may enter your pet's mouth. No treats, no human food, no rawhide or chew bones, no flavored toothpaste, no flavored medications (dewormers, flea/tick tablets). Medications are switched to unflavored alternatives. Store-bought "limited ingredient" foods are not suitable — studies show 33–83% of them contain undeclared proteins. That is why we always use veterinary prescription diets.
Challenge Phase and Long-Term Management
If symptoms improve on the elimination diet, the diagnosis is confirmed by reintroducing the old food. About 80% of dogs react within one week and about 90% within two weeks; cats usually react faster. After this, the pet returns to the elimination diet and individual proteins are tested one at a time. This reveals which proteins are safe and which must be avoided. Food allergy cannot be cured, but when allergens are avoided, your pet can live completely symptom-free without medication. Under veterinary guidance, the elimination diet is an effective and safe process.
Food Allergy Investigations at Our Clinic
At Eläinklinikka Saari, we help you investigate and manage food allergies. We design an individual elimination diet for your pet, treat secondary skin and ear infections at the same time, and monitor progress throughout the process. We also sell elimination diets at our clinic and can advise on choosing the right diet.
Sources
- Mueller R.S., Olivry T., Prélaud P. (2016): Critically appraised topic on adverse food reactions of companion animals (2): common food allergen sources in dogs and cats. BMC Veterinary Research 12:9. ncbi.nlm.nih.gov
- Olivry T., Mueller R.S., Prélaud P. (2015): Critically appraised topic on adverse food reactions (1): duration of elimination diets. BMC Veterinary Research 11:225. ncbi.nlm.nih.gov
- Olivry T., Mueller R.S. (2017): Critically appraised topic (4): can we diagnose adverse food reactions in dogs and cats with in vivo or in vitro tests? BMC Veterinary Research 13:275. ncbi.nlm.nih.gov
- Olivry T., Mueller R.S. (2018): Critically appraised topic (5): discrepancies between ingredients and labeling in commercial pet foods. BMC Veterinary Research 14:24. ncbi.nlm.nih.gov
- Olivry T., Mueller R.S. (2020): Critically appraised topic (9): time to flare of cutaneous signs after a dietary challenge. BMC Veterinary Research 16:158. ncbi.nlm.nih.gov