Advances in Allergy Diagnosis and Treatment
The Compendium of Continuing Education for the
Practicing Veterinarian. 20:3;258-259,1998.
Advances in Allergy Diagnosis and Treatment
Keith A. Hnilica, DVM, MS
Diplomate ACVD
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Page 3 | Contacts
To answer this question one must understand the immune response which causes allergic dermatitis. The current information comes from human studies and suggests that allergic dermatitis is a local cutaneous phenomenon In allergic dermatitis, Langerhans cells phagocytize, process, and present antigens to T lymphocytes. The T cells stimulate B lymphocytes to synthesize allergen specific IgE which is incorporated onto the surface of the Langerhans cells and dermal mast cells. These IgE bearing cells become more sensitized to the antigen and upon repeated exposure these cells respond in an exaggerated manner. What makes allergic dermatitis different from asthma or allergic rhinitis is that the allergic response is focused in the skin; therefore, it is logical that allergy testing the targeted tissue would produce more precise information.
Serologic Allergy Tests offer several advantages. Serum immunoglobulins rise in allergic dogs making it possible to identify and measure antigen specific antibody levels.2 These tests are readily available form several different companies and can be easily performed in any practice environment. There is no special equipment or skill needed, making the test very convenient. In general, the patient does not need to be withdrawn from medications that would interfere with traditional intradermal allergy testing; however, since these tests do measure a component of the immune response, anti-inflammatory medications may alter the results. Discontinuing all steroid containing medications, as one would do before intradermal allergy testing, should be considered before the patient's serum sample is acquired, and some companies include steroid withdraw in their patient preparation requirements. Finally, serologic allergy tests can be utilized in animals with generalized skin lesions when intradermal allergy testing would be impossible.
Intradermal Allergy Testing has been considered the gold standard for diagnosing and treating canine atopy for many years and remains the primary testing method used by most veterinary dermatologists. Intradermal allergy testing allows us to test the skin itself where the allergic response is occurring. Most animals tolerate the procedure well and results are immediately available. Animals should be sedated to minimize any anxiety or stress and must be withdrawn from antihistamines for 10-14 days and from all steroid-containing medications for at least 4 weeks. The antigens used must be carefully stored and maintained to assure high quality testing materials and appropriate antigen stock for immunotherapy vaccine formulation.
Disclaimer
All information relayed within this Web resource is for the general education of veterinary students and practitioners. All references to specific products or companies are not an endorsement of the company or its products. All drug information (especially dosages) should be verified prior to the use of each drug. Any diagnostic tests or treatments should be performed by a veterinarian licensed in the state where the patient resides.
