Canine Atopic Dermatitis

What is atopic dermatitis?

Atopic dermatitis is one of the most common causes of chronic itching in dogs. Atopic dermatitis is caused by an allergic reaction (hypersensitivity) to one or more substances in the environment. Various substances, called allergens, can trigger atopic dermatitis. They are often the same allergens implicated in human allergic conditions such as hayfever and asthma.

What are the symptoms of atopic dermatitis?

Dogs with atopic dermatitis are usually itchy. The face and feet may seem particularly irritated. The skin on some parts of the body may be reddened, moist, or damaged due to scratching or chewing. The ears may also be inflamed, and recurrent ear infections are quite common in these patients. Skin infections can also occur. Less often, dogs with atopic dermatitis have other signs of “allergies” including runny eyes or nose. The symptoms usually start when the dog is 1 to 5 years old. Unlike many humans, dogs do not “grow out” of their allergies – so we almost always recommend treatment.

Why does atopic dermatitis develop?

A combination of factors predisposes dogs to atopic dermatitis. Both their genetic make-up and environment may interact to allow atopic dermatitis to develop. The condition is caused by an inappropriate immune reaction rather than by the allergens themselves.

How are dogs exposed to allergens?

Many allergens are airborne and found nearly everywhere. Some are present year-round (such as housedust, dust mites, and some molds) while others are found at high levels only at some times during the year (such as pollens). Dogs may either inhale the allergens or contact them through the skin.

How is atopic dermatitis diagnosed?

The diagnosis is based on your observations and on our physical examination, as well as by ruling out other causes of allergies, primarily parasites and food.

Can we test my dog for allergies to find out to what he/she is allergic?

Allergy testing is used by most veterinary dermatologists for the purpose of formulating an allergy vaccine, not to make the diagnosis. There are two general methods to perform the test:

Intradermal allergy testing. This test is similar to the test used in humans. Very small injections of approximately 60 allergens are made into the skin on one side of the trunk (after the hair has been clipped). This test requires sedation. Though often referred to as the “gold standard,” this test does involve some subjective interpretation and has been found to be less than 100% reliable, especially when reactions are not particularly strong.

Blood allergy testing. This test attempts to measure antibody levels that your pet has formed against particular allergens. Different testing laboratories’ results may not agree with each other or with intradermal allergy testing results on the same patient.

How is atopic dermatitis treated?

Atopic dermatitis can be treated in many different ways. Limiting your pet’s exposure to his allergens is most effective, but not usually practical – it may mean relocating to a different climate! Other treatments are usually necessary. These include:

Immunotherapy (Hyposensitization)

A series of injections made from allergens that your pet is sensitive to can be given to induce “tolerance” to these substances. When these substances are then encountered in the environment, your pet should be much less sensitive to them. Owners usually give these injections at home.

Traditionally, veterinary dermatologists have based the immunotherapy vaccine ingredients on the results of an allergy test. SkinVet Clinic offers an innovative approach to allergy immunotherapy: RESPIT™, or Regionally-specific Immunotherapy. Allergens are selected on the basis of what occurs in your region, the seasonality of your pet’s signs, and what other pets have responded to in the past. We have assimilated numerous studies that show that allergy testing is often unreliable and that the success of immunotherapy does not depend on allergy testing results. Our RESPIT™ program also utilizes a lower concentration of allergens, to minimize side effects, and a simplified dosing schedule. You and your pet avoid costly allergy testing, while still being able to benefit from immunotherapy, which controls allergy symptoms in about 75% of pets.

Anti-inflammatory medications

Atopica®, fatty acid supplements, prednisone, antihistamines, or other medications may be very helpful to reduce itching in your pet. Atopica® is the only FDA-approved non-steroidal drug for the management of canine atopic dermatitis. A combination of oral medications is often more effective and safer than higher doses of one medication. Since each atopic dog is very much an individual, some dogs need a “trial” with different drugs to find one that works best.

Topical therapy

Medicated shampoos and conditioners can bring relief to many dogs. Bathing removes the allergens that are adhering to the surface of the skin, and the medicated ingredients also help to reduce itching and control secondary infections. Using lukewarm water cools the skin to reduce itching.

Antibacterial and antifungal medications

Because dogs with atopic dermatitis are prone to recurrent bacterial and yeast infections of the skin and ears, we may need to address these infections in addition to treating the atopic dermatitis. These might include Convenia®, Simplicef®, cephalexin, fluconazole, or ketoconazole. Topical therapy with antibacterial and antifungal shampoos, like MalAcetic®, can help resolve and prevent infections.

It is also very important for any dog with atopic dermatitis to be on a year-round, comprehensive flea control program. Atopic dogs tend to be more sensitive to the bites of fleas, so we would like even occasional fleabites to be prevented. The flea products that we most often recommend are Vectra® 3D, Comfortis®, and Revolution®.

Managing this lifelong condition takes some patience. By using various combinations of therapy, and altering the treatment when needed, we can help atopic dogs feel and look their best.