Allergies are a common cause of chronic itching in dogs and sometimes cats. Chronic ear infections may be a result of these allergies also. Our pets can be allergic to pollens, molds, mites, foods (typically protein sources such as beef or chicken or carbohydrates such as corn or wheat) and insects such as fleas. It should be noted that food allergies are typically developed over time to foods the animal has been eating for weeks, months, or years. Fleas are the most common allergy, followed by atopy (affecting 10% of dogs) and food allergies (affecting about 1% of dogs). Secondary skin infections with bacteria or fungus are common as well and contribute to the itching.
Treatments for atopy include steroids such as predisone, antihistamines, fatty acid supplements, medicated baths, immune suppressants (Atopica), and desensitization injections (immunotherapy – Greer Labs). Immunotherapy injections are helpful for 60-70% of allergic dogs, with improvement occurring within 2-12 months. Food allergies can only be diagnosed with a strict hypoallergenic diet trial lasting 8-12 weeks. They are then treated by continuing the special diet or isolating the specific allergy and avoiding it. Antibiotics and anti-fungal medications are commonly needed to control secondary infections.