Allergies don’t just affect people – dogs get them, too

EDITOR’S NOTE: Dr. Peter Kintzer will write this column on the second Friday every other month.

Yes, dogs can become allergic to various things. One of the most common types of allergies diagnosed in dogs is environmental allergies, also called atopy.

Canine atopy is caused by a hypersensitivity reaction to substances (allergens) in the environment that are inhaled or absorbed by the skin of a genetically susceptible dog. Examples of such allergens are dust mites, wool, feathers, and various molds and pollens. Some breeds of dogs seem to be predisposed to developing environmental allergies. These include Labrador retrievers, golden retrievers, Boston terriers, Westies, Scotties, bulldogs, Pugs, boxers, Dalmatians, Lhasa apsos and German shepherds.

In most atopic dogs, clinical signs are first noted between 1 and 3 years old. However, in some cases, the age of onset is as young as 6 months or in middle age. Clinical signs may worsen over the first few years the dog is affected.

The clinical signs of atopy are itchiness, licking and biting of the feet, scratching and chewing at the armpits and groin area, and rubbing the face. The skin often appears inflamed, and other lesions that may be present include hair loss, a dry or greasy coat, excoriations, scabs and crusts, and increased pigmentation of the skin.

Unlike people with environmental allergies, respiratory symptoms are uncommon. Secondary skin and/or ear infections, which may be recurrent, are common and in some dogs are the major manifestations of the allergies.

The intensity of the symptoms varies from patient to patient and can be mild to severe. Atopy can be seasonal or nonseasonal. A patient with seasonal allergies may be significantly affected during certain months, with minimal to no symptoms at other times of the year. Patients with seasonal allergies can progress to nonseasonal status if they become sensitized to additional environmental allergens.

The diagnosis of environmental allergies involves the recognition and demonstration of compatible historical and clinical findings, as well as the exclusion of other dermatologic disorders with similar symptoms. There are two methods of allergy testing available to try to determine those things to which your dog may be allergic.

The method usually preferred by dermatologists is an intradermal skin test (like a scratch test). After sedation and clipping a small patch of hair on one side of the chest, very small amounts of the potential allergens are injected into the skin. The specialist then “reads” the reactivity of the various allergens within 20-30 minutes after the injections.

The second method is a blood test that is meant to measure antibodies to various environmental allergens. In some cases, both intradermal skin testing and the blood test are performed to evaluate the patient. Determination of what the patient is allergic to can be very helpful in formulating a program of therapy for your dog’s allergies.

Once a pet is diagnosed with atopy, several different forms of treatment are available. What is recommended depends on the severity of symptoms, age of the dog and seasonality of symptoms. The therapeutic plan must be individualized for each patient, and a combination of treatments is often employed.

One option is to avoid what the dog is allergic to. Complete avoidance of most allergens is usually not possible or practical, but reduction of exposure may be helpful in some cases. An example of this is frequent bathing of an atopic dog at an interval recommended by a veterinarian (and using a shampoo and conditioner they have prescribed).

The next means of therapy is hyposensitization (also called allergen specific immunotherapy), or allergy shots. This consists of a series of injections of diluted allergens given under the skin, typically administered by the owner at home. The intent of the injections is to make the dog less sensitive to the offending allergens by altering the allergic response into a more normal one. About 70 percent of owners report a beneficial response to hyposensitization.

Another treatment for environmental allergies is the use of various drugs. Antihistamines can benefit the atopic dog, but are infrequently sufficient alone to adequately control symptoms, except in milder cases. Recently, cyclosporine has been demonstrated to be an effective treatment in many atopic dogs and may be safer than cortisone drugs such as prednisone for long term use. Cortisone drugs such as prednisone can be used to treat environmental allergies. To minimize potential side effects, the patient is usually given the lowest effective dose and only when necessary. Dogs receiving cortisone drugs or cyclosporine need laboratory testing done before and periodically during therapy.

Environmental allergies in dogs are controlled, not cured. Frequent visits to the veterinarian may be necessary, especially early in the course of treatment. As previously stated, an individualized multimodality treatment plan is often needed. In most dogs, the allergy symptoms can be controlled or reduced and the quality of the patient’s life improved.

Your Pet is published on the second and fourth Fridays of each month. Peter Kintzer, DVM, is a veterinary internist, board certified by the American College of Veterinary Internal Medicine. Kintzer is associated with the Animal Medical Center of New England in Nashua. Call 821-7222 or visit www.amcne.com for more information or to make an appointment.