This article is a guide to help you understand and address allergies that can cause your pet to have dermatitis. IE: flea allergy dermatitis, inhalant allergy/atopic dermatitis, and food allergy dermatitis.

Allergic dermatitis in dogs and cats refers to itchy (pruritic) skin diseases with multiple causes.

The primary sign in dogs and cats is itchy skin. Animals may scratch, bite or lick themselves continuously which can cause hair loss and skin damage. The fur at the lick-site may turn pinkish and/or the skin may appear red and/or thickened. You may notice an odor, greasiness, and/or red spots, pimples, or scabs. There may be ear discharge, head shaking, and ear odor and/or infection. Animals with food allergies may have gastrointestinal (GI) and skin issues at the same time. If the dermatitis is a result of fleas you may see fleas or their droppings (flea dirt) in the fur.

Flea allergy dermatitis is caused by an animal’s allergic reaction to the saliva from the bite of the flea. In some animals, only one flea bite is needed to set off a severe skin reaction. Atopic dermatitis (atopy) – involves an abnormal reaction by an animal’s immune system when it comes into contact with substances or organisms (allergens) in the environment that do not cause an allergic response in normal animals. Common allergens in dogs with atopy include pollen, grasses, weeds, trees, plant fibers, mold, household cleaners, dust, dust mites, various grains, insect bites, animal dander, and chemicals. Food allergy is an allergic response to some foods. The most common foods causing reactions for both dogs and cats are beef, chicken, dairy products, eggs, wheat, corn, and soy. For cats, fish is also a common offender. It is believed that food allergy and atopy are likely inherited conditions. All of these conditions may be present in the same animal, as can skin mites that cause itching.

Allergy suspects are checked for skin mites and ringworm (hair/skin fungus) to rule out other causes. If these tests are negative, allergic dermatitis is usually suspected.

All animals should be checked for fleas and treated to remove them. All animals at the Connecticut Humane Society are treated for fleas (and intestinal parasites) and they are re-treated monthly while they remain at the Society. Anti-itch medications (like Benadryl or cortisone) and/or antibiotics may be administered to treat severe itching or secondary infections. Some animals need repeated courses of therapy. Animals suspected of having a food allergy are prescribed a specialized hypoallergenic diet and must be restricted to only this food.

Continue any prescribed medications and/or diet.

Continued or recurrent skin or GI signs.