Allergy Testing in Practice – Is it worth it?

When one thinks of allergy testing, it is typically in the context of intradermal tests or serum tests for allergenspecific IgE to diagnose atopic dermatitis. However, I will also discuss elimination diets to diagnose adverse food reactions in this lecture.

Atopic dermatitis is a fairly common cause of skin disease in the dog and increasingly diagnosed in the cat as well. Serum tests for allergen-specific IgE and skin testing have all been advocated as diagnostic aids, but neither is a good way to diagnose atopic dermatitis!!! It should be diagnosed based on the history and clinical signs as well as diagnostic trials to rule out diseases with similar clinical presentation. There are only three reasons to identify the offending allergens in an atopic animal:
• Curiosity
• Some owners will simply want to know what their dog is allergic to without any effect on treatment of the condition.
• Avoidance
• This is initially the most common reason mentioned by owners in support of further testing. However, it is extremely rare that we can avoid allergens that are airborne.
• Immunotherapy
Allergy shots or immunotherapy is the major reason for us to recommend identifying the offending allergens in an atopic animal. This treatment aims at ‘getting the immune system used to the allergens’ and hopefully eliminating or at least decreasing the pruritus and/or predisposition to infection. This is a very safe and fairly easy treatment, that may replace concurrent therapy or at least decrease the dose needed to control clinical signs. Approximately 60% of the patients show a good to excellent response, 20% improve moderately and 20% do not show any improvement at all. [...]