by: Jenise Daigle, DVM, DACVD
Atopic Dermatitis (AD) is a diagnosis of exclusion. Diagnosis is based on history, clinical signs, and ruling out other causes of pruritus. A full dermatologic workup is necessary because AD is a diagnosis of exclusion. No specific diagnostic tests exist for Atopic Dermatitis.
Intradermal Allergy Test (IDT): IDT can be used to select allergens for allergen-specific immunotherapy (ASIT) or identify allergens for avoidance. However, IDT cannot be used to diagnose AD. Both normal and atopic patients can demonstrate positive reactions on an IDT.
Serologic Allergy Test (SAT): Similar to IDT, SAT cannot be used to diagnose AD. Elevated allergen-specific IgE levels can be found in both normal and atopic patients.
It is important to rule out other causes of pruritus. Allergy testing should be used to help formulate immunotherapy for treatment, not for diagnosis of the condition.