Canine Atopic Dermatitis

Atopic dermatitis (allergic dermatitis, inhalant dermatitis,atopy) is an inherited predisposition to develop allergicsymptoms after repeated exposure to some otherwise harmlesssubstance, and "allergen" such as dust, dust mites, grasses, orpollen. Most dogs begin to show their allergic signs between 1and 3 years of age. A few dogs may show clinical symptoms at 6months of age. It is also unusual to see clinical symptoms startafter 7 years of age. Because of the hereditary nature of the disease, several breeds,including golden retrievers, most terriers, Irish and Englishsetters, Lhasa apsos, dalmatians, bulldogs, beagles, miniatureschnauzers and Chinese Shar Peis, are more commonly "atopic."Atopic animals usually rub, lick, chew, bite, or scratch attheir feet, muzzle, ears, armpits, or groin, causing hair lossand reddening and thickening of the skin. In some cases, severaloffending substances can "add" together to cause an animal toitch where each individual substance alone would not be enoughto 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 yeastinfections of the skin. Sometimes, eliminating some but not allof the problems may cause a dog's or cat's itchiness to go away.Therefore, it is important to treat any other problems thatcould be making your pet itch while dealing with allergy.Diagnosis of atopic dermatitis is based on clinical sighs (areasof itching) and an initial seasonality of 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 bloodtest to detect reaction to the specific allergic substance.Treatment can include avoidance of the substance, therapy tocontrol the itching (symptomatic therapy), or specific therapy(desensitization vaccine) in an attempt to desensitize your petto the specific substances to which he or she is found to beallergic.Complete avoidance of the allergic substance may not bepractical, but decreased exposure may be feasible. If your petis allergic to pollen, decreasing the outdoor exposureespecially at dusk and dawn is helpful. Your pet should never bewalked through fields with high grass or weeds and should not beoutside when the lawn is cut. If your pet has an allergy to fungi or molds, it should not bekeep in rooms with high moisture levels (bathroom or laundryroom) or allowed to be in areas of increased dust (crawl spacesunder the house). Control of house dust or mites in the home canbe a major undertaking, consisting of removing carpeting,covering mattresses, regular washing of the bedding,high-efficiency vacuuming, avoiding stuffed toys, and frequentdamp mopping of the areas most frequented by your pet.Antihistamines and fatty acids, when given in combination, candecrease the itching sensation in about 10 to 20 per cent ofatopic pets. Your pet can take antihistamines and fatty acidsfor life with no long-term problems. The only side effectusually seen with antihistamines is drowsiness. Severaldifferent types of antihistamines may need to be tried to findthe one that works the best. These two combined therapies(antihistamines together with fatty acids) should be given a fewmonths 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-itchproperties may also be of benefit. These products usually needto be applied daily (sprays, gels, lotions) or a few timesweekly (shampoos, cream rinses, leave-on conditioners). It ismost important that your pet be bathed in cool water becausewarm or hot water increases the itching sensation.Steroids (e.g., prednisone, cortisone) can be formulated foryour 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 areneeded (every few weeks). Sixty to 80 per cent of animalsimprove with these vaccines. However, desensitization takestime. 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 thevaccine 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 thetime and effort in utilizing symptomatic therapy only on yourpet or while your pet is undergoing the process ofdesensitization. Only by trial and error can the optimal therapybe formulated. Time and patience are the keys!The above is general veterinary information. Do not beginany course of treatment without consulting your regularveterinarian. All animals should be examined at least once every12 months.