Food allergies can cause cats and dogs to scratch excessively, lose or pull out their fur, or develop scabs or sores around their necks. However, there are other possible triggers for these problems, including parasites such as fleas, fungal or bacterial skin infections, other medical conditions, and other allergies. It’s important to bring your pet in for a veterinary check-up to rule out medical problems before assuming that an allergy is the culprit.
Food Allergies in Cats and Dogs
Food allergies cause significant suffering for animals, and they are quite common due to the variety of artificial ingredients, fillers and processed proteins that pets consume in commercial foods. In some cases, an animal’s immune system will attack ingredients it doesn’t recognize as foreign invaders, and this often manifests as skin irritation. Pets may not have any gastrointestinal symptoms at all, which is why many owners don’t think of food allergies when searching for an explanation.
Pets can develop allergies to foods they have been eating for years, so allergies may be the cause of a pet’s itchy skin even if the diet has not been changed recently. While parasitic skin irritations are more inclined to be seasonal, food allergy reactions can occur all year round, and itchy skin caused by food allergies does not usually improve with cortisone medications.
Pets that are prone to food allergies may also have flea allergies, and the two allergies can exacerbate one another. In some cases, just getting rid of the fleas eliminates the symptoms of the food allergy as well. If the symptoms persist once the fleas are gone, your pet should be switched to a hypoallergenic diet.
Hypoallergenic Diets for Cats and Dogs
Allergies develop through exposure, and so most hypoallergenic diets incorporate proteins and carbohydrates that your cat or dog has never had before. As dairy, fish, and beef are responsible for 80% of food allergies in cats, these items should be avoided. Dogs are most commonly allergic to wheat, dairy, and beef.
Protein sources used in hypoallergenic diets include venison, egg, duck, kangaroo, and types of fish not usually used for pet food. Carbohydrate sources include potatoes, peas, and rice. Veterinarian Wendy Brooks recommends a combination of duck and peas for cats, which is available in both wet and dry formulations, and potato-and-duck-based foods for dogs.
Most pets with food allergies respond well when switched to a store-bought hypoallergenic diet, but occasionally an animal suffers from such extreme allergies that a homemade diet is the only option. In this case, the diet should be customized with the aid of a veterinarian.
Making the Switch to a Hypoallergenic Diet
You can discover whether a food intolerance or allergy is causing your pet’s itchy skin by feeding her a hypoallergenic diet for 14 days and then switching back to the old diet to see if the symptoms abate with the hypoallergenic diet and recur with the old one. Stay with the old diet for 14 days after trying out the new one, and if the symptoms reappear, switch back to the hypoallergenic diet permanently. During the test of the two diets, no medications, edible toys, or treats should be given, as these might influence the result.
If your pet does not respond positively to a hypoallergenic diet, it is possible that food allergies are not the problem. Your pet may have an inhalant allergy, which can be treated with special baths or allergy shots and other medications.
Allergies can be extremely uncomfortable for pets and symptom relief is critical. Consult your veterinarian to discuss options.
Reference: Brooks, W.C., DVM, DipABVP, Veterinary Information Network Inc. (2007). “Food Allergies” and “Food Allergy Myths.”