What are the signs of food allergies in dogs?

Ingredients most often reported in food-allergic dogs are proteins such as beef, dairy, chicken and wheat, followed by others including lamb, soy, egg and fish. These are common partly because they are common in dog foods. Any protein a dog has eaten can become a trigger, so your veterinarian chooses a diet trial based on what your dog has eaten before.

Food allergy usually develops after a dog has eaten an ingredient for months or years, not after the first meal, which is why a long-time food can suddenly seem to cause problems. During an elimination trial, itching may take several weeks to improve. When the old food is reintroduced, symptoms often return within days to two weeks.

Veterinary guidance generally calls for about six to twelve weeks on a strict elimination diet, and many vets aim for at least eight weeks before the skin fully improves. Digestive signs often settle sooner. The trial only works if the dog eats nothing else, including treats, dental chews, flavored medicines and table food, so the whole household needs to follow it.

Not necessarily. Most food allergies in dogs are to proteins such as beef, chicken or dairy, not to grains, so a grain-free diet that still contains the problem protein won't help. Veterinarians usually recommend a hydrolyzed-protein or novel-protein diet for an elimination trial. Talk to your vet before choosing a diet for an allergic dog.

Veterinary dermatologists generally do not recommend blood, saliva or hair tests to diagnose food allergy in dogs, because results don't reliably match which foods cause symptoms. A strict elimination diet followed by reintroducing the old food is the accepted way to diagnose it. Blood or skin testing is used for environmental allergies, mainly to plan immunotherapy.

A food allergy involves the immune system and typically causes itchy skin and ear problems, sometimes with digestive signs. A food intolerance doesn't involve the immune system and mostly causes stomach upset, such as vomiting, diarrhea or gas, for example after a sudden diet change or rich table food. Your veterinarian can help tell them apart.

People are much more often allergic to the dog itself, specifically proteins in dander, saliva and urine, than to dog food. Handling dog food rarely causes problems unless a person has a food allergy to an ingredient. If you sneeze or itch around your dog, allergy testing for you can confirm the trigger and open up treatment options.