Atopy is a pruritic (itchy) skin disease of animals that is caused by an allergy to substances in the environment that are contacted through the air, either by absorption through the respiratory tract or contact through the skin. Atopy is thought to be an inherited disease. It is the second most common allergic skin condition in dogs; only flea allergy dermatitis is more common.

Symptoms of atopy usually begin relatively early in life, often by one year of age. Symptoms usually are seasonal at first, with most dogs showing clinical signs in the summer months when airborne allergens (such as plant pollens) are present in higher concentrations. As atopic dogs age, their symptoms tend to become less seasonal as they become allergic to more substances. Eventually, their itchiness can occur year-round.

Dogs with atopy are usually itchy, particularly the hands and feet. The skin may be red and irritated due to scratching, and the ears may also be inflamed. The symptoms of food allergy are difficult to distinguish from those of atopy.

What to Watch For

Chewing at the paws

Scratching the muzzle or rubbing it on the ground or with the paws

Scratching the ears

Shaking the head

Diagnosis

Diagnostic tests are necessary to rule out other skin diseases, as well as to support the diagnosis of atopy. These tests may include:

A complete medical history and perform a thorough physical examination, especially checking the ears and the skin of the face and paws. Often, abnormalities may not be detected on the physical examination of dogs with atopy. Occasionally, redness between the toes or around the muzzle of the face is the only finding.

Skin scrapings to eliminate other diagnoses such as demodectic or sarcoptic mange (caused by mites).

Fungal culture to rule out ringworm (also called dermatophytosis).

Skin testing (or occasionally blood testing) to determine specific allergens to which your pet may be allergic.