Allergies are a very real problem in our pets. Dogs and cats manifest allergies differently than humans. Allergies manifest through the skin of dogs and cats whereas humans exhibit more upper respiratory signs. Our pets, therefore, exhibit itching and scratching, redness of feet and belly, shaking the head and ears, and chewing the feet.
There are three main categories of allergies: atopy (seasonal and environmental), food allergies, and flea reactions. Almost without exception, pets have multiple allergies. Therefore if we suspect a seasonal allergy, a food allergy should be considered as well.
Atopy is also known as seasonal and environmental allergies. The potential list is truly endless. If the allergen is outdoor and seasonal, then the allergy will occur just a few times a year. If there is an indoors environmental allergen, then the pet may exhibit the allergy throughout the year. The classic clinical signs are face rubbing, feet licking, scratching the flanks and abdomen, and generalized itchiness. Allergens are inhaled as well as absorbed. Therefore the allergens are concentrated in the feet and are a likely reason for excessive foot/pad chewing. For this reason, we describe atopy as "Face and Feet".
Food allergies can also have an endless potential list. One should not assume one allergy over another (i.e. wheat gluten, beef, etc). The classic clinical signs for food allergies are recurrent ear disease and rectal problems (itching, licking, scooting). For this reason, we dub food allergies as "Ears and Rear".
Flea allergies manifest with a thinning hair pattern just over the rump at the base of the tail. Fleas may or may not be seen! Fleas may be in the inguinal region, around the ears, and etc, but the dermatologic lesion will be at the base of the tail.
Secondarily the skin will respond to these allergens with redness, hair loss, crusting, scabbing, flakiness, and infection.
Diagnosing allergies begin with a detailed history and physical examination. Clinical signs and locations of dermatitis often direct us to the type of allergy. Allergies can only be specifically diagnosed through either skin or blood testing. Food allergies can be diagnosed through blood testing or through an extended dietary food trial. Flea allergens are diagnosed through physical examination.
Treatment consists of identifying the underlying allergen and preventing exposure if possible. Antihistamines and steroids are often utilized with varying success. Identification and production of an allergen serum can be used to retrain how the body responds to allergens. The only real treatment of food allergy is through a restricted diet. Flea prevention and treatment is the primary method of preventing flea allergies.