Atopic dermatitis is one of the most common skin diseases in veterinary medicine.Allergen-specific immunotherapy (ASIT) is a well-established treatment in dogs, and most pet owners are familiar with“allergy shots” for people. In humans, ASIT has been reported to be effective treatment for seasonal allergic rhinitis, allergic bronchitis, allergic asthma, and stinging-insect hypersensitivity; however, its efficacy in the treatment of human atopic dermatitis is unclear. In dogs, numerous open uncontrolled studies support the use of ASIT as a treatment,with response rates ranging from 50% to 100%.Of note, only one prospective, double-blind, placebo-controlled trial has assessed the efficacy of ASIT in dogs; 59% of dogs showed a greater than 50% decrease in pruritus compared with 21% of dogs receiving placebo. In both dogs and humans, the time to maximal clinical benefit is unknown, as is the total duration of therapy. Adverse reactions are rare in humans (2%–3%) and have included local injection site reactions, rhinitis, asthma, and anaphylaxis, usually within 30 minutes of administration.Adverse reactions in dogs are also rare; the most common is increased pruritus. Subcutaneous administration of allergen is the standard route for both humans and dogs. In veterinary medicine, however, ASIT is commonly administered by pet owners, whereas humans must receive the injection at their doctor’s office.The most common reasons that people discontinue their own treatment are the long treatment duration and inconvenience. Studies in humans have established optimal doses of allergens and frequency of administration. In dogs, 1 study showed that 49% of owners discontinued ASIT because of a lack of improvement.The optimum dose of allergen, effect of concurrent medications, and true efficacy in dogs require additional studies.

In the diseases for which it is indicated, ASIT in both dogs and humans has many practical similarities that will help clients understand the treatment protocol and expected results. It is important to stress to clients that it can take up to 1 year to see maximum benefit and during this year the dog needs to be closely followed so therapy can be adjusted when needed.What is frustrating in veterinary medicine is the lack of large-scale controlled studies similar to those conducted in humans that have resulted in standardized treatment protocols. In veterinary medicine, the Task Force on Canine Atopic Skin Disease, consisting of 12 to 15 members, is working on just that—standardizing the treatment of canine atopy as well as supporting needed research.—Karen A.
Moriello, DVM, Diplomate ACVD

A review of allergen specific immunotherapy in human and veterinary literature. Loewenstein C,Mueller RS.VET DERMATOL 20:84-98, 2009.