When is allergy testing performed and what is its purpose?
The diagnosis of atopy is based on history, consistent clinical signs and ruling out other causes of itchy skin and otitis externa. Occasionally, non-atopic dogs and cats can have positive allergy test results – this is why it is vitally important that the correct diagnosis has been made first, before resorting to these tests, and why cases are best dealt with by a veterinary dermatologist.
Once a diagnosis of atopy is made, cat and dog allergy testing can be performed to discover what allergens are significant if we are to consider trying to reduce allergen exposure. This may help to reduce symptoms but is unlikely to abolish them completely. Allergy testing is done primarily to decide upon which allergens to include in a treatment called Allergen-Specific Immunotherapy (ASIT).
Two methods of allergy testing can be used. Intradermal Skin Testing (IDST) is still considered the gold standard test amongst veterinary dermatologists and there is also the choice of Serological Allergy Testing. These tests measure allergy in different ways – IDST measures allergen specific antibody bound to cells in the skin called mast cells, which play an important part in the mechanism of itchy skin associated with atopy and serologicial allergy testing measures allergen specific allergic antibody in the bloodstream.