Atopic dermatitis or “atopy” is caused by a hypersensitivity to inhalation of or contact with certain substances. Substances frequently responsible for the allergy (antigens) include pollens, feathers, wool, house dust, mites, mold, and smoke. Any substance that can be inhaled has the po tential to cause a hypersensitivity reac tion.
Atopy is the second most common allergic skin disease in dogs and cats (flea allergy is the first.) Combinations of hypersensitivity to inhaled substances, fleas, and/or food are common. Since atopic dermatitis is an inherited problem, pets with the disease should not be bred. Dog breeds most often affected include the terrier breeds, Dalmatians, Schnauzers, and Golden and Labrador retrievers.
The onset of signs usually occurs between one and three years of age. Initially, signs may be mild and seasonal, but may progress to more severe, year-round problems.
Atopy in dogs creates an itching sensation in the feet, face, ears, and armpits. Dogs with this allergy will intermittently or constantly scratch, lick, and rub these areas. This self-induced trauma may cause the skin to become red and irritated, and often leads to infection, hair loss and thick, dark skin. Ear and eye inflammation and infection also occur frequently. The skin may be come scaly and either excessively dry (seborrhea sicca) or greasy, waxy, and smelly (seborrhea oleosa). Inhaled allergies may also cause sneezing, eye discharge, asthma, intestinal upset, and reproductive abnormalities.
Cats with atopy may rub and scratch the ears and face, creating skin bumps, crusts, and hair loss. Allergic cats may also develop eosinophilic plaques and granulo mas (red or yellow, firm, raised areas), or indolent ulcers (swollen, ulcerated lips).
Diagnosis of atopy is based on history, clinical signs, and laboratory results. Because atopy may be associated with or mimic other diseases, laboratory testing is often recommended. Blood tests are recommended to rule out internal disease and hormonal abnormalities, especially hypothyroidism. Skin scrapings may be done to check for mange. In cases of skin infection, cytology or cultures may be taken to determine the presence of bacteria or yeast and assist in the selection of appropriate antibiotics. Occasionally, skin biopsies will be indicated. Determination of the specific substances causing the allergy requires a special blood test, or skin testing done by a veterinary dermatologist.
The best way to prevent allergic skin disease is to avoid exposure to the problem substances (antigens) identified by skin or blood testing. Since avoidance is often not possible or realistic, medication is usually prescribed to decrease the allergic response.
Hyposensitization (immunotherapy) is often effective in atopic patients. Response to hyposensitization will be less in atopic pets that also have flea allergy or food allergy. A liquid solution of antigens is formulated according to the skin or blood test results. Initially, injections of these antigens are given frequently, then the time between injections is gradually increased. The skin problems may resolve in as little as one month, but it may take longer than one year of treatment.
Anti-inflammatory drugs (corticosteroids) are usually quite effective in immediately decreasing the itch and irritation in atopic pets. Cortisone injections may be used when your pet is very itchy, then cortisone pills may be prescribed. These medications may cause in creased appetite, water drinking and urination. Corticosteroids are strong drugs and can have side effects; therefore, it is important to carefully follow the instructions. After control of itch is achieved, the amount and frequency of medication is stopped or decreased to the minimum effective dose every 2 or 3 days. Because of significant side effects, steroid pills should never be given every day for longer than 5 days unless specifically instructed by the veterinarian.
Antihistamines may reduce itch and improve coat condition. Antihistamines may be used with steroids to reduce the steroid dose required. Because response is variable, a sequence of different antihistamines may be prescribed to determine which medication and dosage is the most effective.
Fatty acid supplementation can aid in itch relief and often enhances the effect of antihistamines. The dosage given should be 2 to 4 times the suggested dosage on the bottle.
For pets with atopy and flea allergy, flea control is imperative for effective relief.
Frequent use of appropriate shampoos will often improve skin and coat condition and decrease itch. Antibacterial shampoos are useful in pets with secondary skin infections. Tar or follicular flushing shampoos are prescribed for dogs with scale and greasy or waxy seborrhea. Moisturizers are used for dry coat conditions. A bath in cool water, with or without addition of an oatmeal shampoo or rinse, is helpful in reducing the itch. A variety of topical sprays are available containing steroids, antihistamines, anesthetics, antibiotics, desiccants, or moisturizers.
Atopy can be a very frustrating condition for both the owner and pet. Patience is necessary in most cases while the most beneficial treatment for your pet is found. Please do not hesitate to ask questions of your veterinarian or the staff at Alicia Pet Care Center. We are here to make sure that you are providing the best quality of life for your “baby.”