It's allergy season for dogs, too

USA Today (Society for the Advancement of Education), April, 2006

Unlike people who display respiratory symptoms due to their allergies, dogs most commonly develop skin rashes. Understanding canine allergies and their management is the first step in protecting your dog this spring, points out Novartis Animal Health US, Inc., Greensboro, N.C.

Skin is a dog's single largest organ, representing 12% of an adult canine's body weight. It is a temperature regulator, an important protector from the environment, and the primary indicator of allergic reactions. Offending environmental allergens frequently enter the dog's body through direct contact with the skin. Canine skin disease is not that unusual. The most frequent signs include redness (erythema), itching (pruritus), and hair loss (alopecia).

Another common canine allergy is atopic dermatitis, an inflammatory, itchy, allergic skin disease caused by a hypersensitivity to common environmental allergens such as pollen, mold, or dust mites. Atopy, the most common allergic condition in dogs--7,000,000 are affected--tends to appear between six months and three years of age and often is a lifelong condition that can lead to hair loss, red skin, lesions, and secondary infections.

Another is flea allergy dermatitis, an allergic reaction to flea saliva. Most dogs show immediate hypersensitivity with the primary clinical sign being itchiness. Lesions from the reaction usually appear on the back, tail, or hips.

Food allergy, meanwhile, is a response to ingredients that causes either skin or gastrointestinal tract disease. Skin lesions from this condition most commonly appear on the face, ears, or hips. Finally, allergic contact dermatitis is an inflammation of the skin caused by a delayed hypersensitivity to contact with irritants such as fibers, dyes, detergents, and medications.

Corticosteroids are the class of curative drugs most often used since they provide quick relief of itching and skin inflammation. They come in a variety of forms, including injections, tablets, and topical creams and sprays, but offer only temporary relief. Long term, corticosteroids could induce side effects such as an enlarged liver; excessive thirst, hunger, and urination; hair loss; weight gain; and Cushing's disease.

Human antihistamines are the second-most prescribed class of drugs. They occasionally provide a relatively inexpensive and quick answer to the itchiness, but patient response is variable and unpredictable. Veterinarians often have to change the type of antihistamines or vary doses to find one that is effective. Less than one-third of itchy dogs will respond to this therapy.

Commonly referred to as "allergy shots," immunotherapy also is offered by dermatologists and many general practitioners. Small doses of allergens are injected to desensitize or dampen the immune system's response. Numerous injections are required and treatment is lifelong. Response can be slow, complicated, and expensive.