Atopic dermatitis (allergic dermatitis, inhalant dermatitis, atopy) is an inherited predisposition to develop allergic symptoms after repeated exposure to some otherwise harmless substance, and "allergen" such as dust, dust mites, grasses, or pollen. Most dogs begin to show their allergic signs between 1 and 3 years of age. A few dogs may show clinical symptoms at 6 months of age. It is also unusual to see clinical symptoms start after 7 years of age. Because of the hereditary nature of the disease, several breeds, including golden retrievers, most terriers, Irish and English setters, Lhasa apsos, dalmatians, bulldogs, beagles, miniature schnauzers and Chinese Shar Peis, are more commonly "atopic."

Atopic animals usually rub, lick, chew, bite, or scratch at their feet, muzzle, ears, armpits, or groin, causing hair loss and reddening and thickening of the skin. In some cases, several offending substances can "add" together to cause an animal to itch where each individual substance alone would not be enough to cause an itching sensation. These substances include not only airborne allergens (e.g., pollens) but also allergens in food and allergens from parasites (e.g., fleas) and itching caused by bacterial or yeast infections of the skin. Sometimes, eliminating some but not all of the problems may cause a dog’s or cat’s itchiness to go away. Therefore, it is important to treat any other problems that could be making your pet itch while dealing with allergy.

Diagnosis of atopic dermatitis is based on clinical sighs (areas of itching) and an initial seasonality ot the skin problem. However, many dogs soon begin to scratch and rub year round. Specific therapy is based on the results of a skin test or blood test to detect reaction to the specific allergic substance.

Treatment can include avoidance of the substance, therapy to control the itching (symptomatic therapy), or specific therapy (desensitization vaccine) in an attempt to desensitize your pet to the specific substances to which he or she is found to be allergic.

Complete avoidance of the allergic substance may not be practical, but decreased exposure may be feasible. If your pet is allergic to pollen, decreasing the outdoor exposure especially at dusk and dawn is helpful. Your pet should never be walked through fields with high grass or weeds and should not be outside when the lawn is cut. If your pet has an allergy to fungi or molds, it should not be keep in rooms with high moisture levels (bathroom or laundry room) or allowed to be in areas of increased dust (crawl spaces under the house). Control of house dust or mites in the home can be a major undertaking, consisting of removing carpeting, covering mattresses, regular washing of the bedding, high-efficiency vacuuming, avoiding stuffed toys, and frequent damp mopping of the areas most frequented by your pet.

Antihistamines and fatty acids, when given in combina-tion, can decrease the itching sensation in about 10 to 20 per cent of atopic pets. Your pet can take antihistamines and fatty acids for life with no long-term problems. The only side effect usually seen with antihistamines is drowsiness. Several different types of antihistamines may need to be tried to find the one that works the best. These two combined therapies (antihistamines together with fatty acids) should be given a few months before a decision is made concerning their effectiveness.

Products applied topically to the skin (shampoos, cream rinses, leave-on conditioners, gels, lotions, sprays) with anti-itch properties may also be of benefit. These products usually need to be applied daily (sprays, gels, lotions) or a few times weekly (shampoos, cream rinses, leave-on conditioners). It is most important that your pet be bathed in cool water because warm or hot water increases the itching sensation.

Steroids (e.g., prednisone, cortisone) can be formulated for your pet on the basis of results of a skin test or blood test. These vaccines are usually given for the lifetime of your pet. After an initial series of injections, periodic boosters are needed (every few weeks). Sixty to 80 per cent of animals improve with these vaccines. However, desensitization takes time. Improvement may not be seen for 3 to 6 months or longer. If results are not seen in 9 to 12 months, a reevaluation of the vaccine usage is necessary.

Allergies are a lifelong problem and tend not to just go away. The best chance for success is realized when you can spend the time and effort in utilizing symptomatic therapy only on your pet or while your pet is undergoing the process of desensitization. Only by trial and error can the optimal therapy be formulated. Time and patience are the keys!