It is generally thought to be not helpful in the diagnosis of food allergies. It is generally performed by a dermatology specialist and involves injecting minute quantities of numerous allergens into the skin and measuring the skin's response. In recent years, blood testing for allergy diagnosis has become more popular. This methodology measures the level of allergen specific antibodies in the blood in order to determine the animal's sensitivity to the allergen involved. Again, this is most useful in diagnosing allergies to airborne allergens, not food allergies.
Blood testing does have certain advantages over skin testing.
The necessary blood samples can be drawn by any veterinarian and submitted to a laboratory for allergy assay. The costs of blood testing may be slightly lower than skin testing in some areas. However, many veterinary dermatologists feel that intradermal skin testing is still the preferred method to diagnose these common conditions. In my practice, if allergy testing is indicated I first offer a referral to a dermatologist for skin testing. If the owner declines such a referral, then we can offer blood testing as an alternative.