Diagnosis of allergic dermatitis is based on history, correct identification of clinical signs, and exclusion of other diseases that cause itching.
Therefore, the first step is a thorough clinical examination that includes the necessary tests to rule out other differential diagnoses, particularly ectoparasites.
Like people, animals can develop allergic or intolerance reactions to one or more components of their diet. The most common cause of food allergy is the ingestion of animal protein (beef, chicken, fish, milk, eggs) or plant protein (soy, wheat, corn).