Allergy Shots May Bring Relief to Itchy Dogs

Immunotherapy may be an effective treatment option

Is something itching at your dog?

If an allergy is to blame, it probably falls into one of three categories, according to Dr. Scott Miller, who recently completed an internship in small animal dermatology at the University of Illinois Veterinary Teaching Hospital in Urbana. The options are flea allergic dermatitis, food allergies, and environmental allergies, also called “atopy” and “atopic dermatitis.”

“Flea allergy is considered the most common allergy affecting dogs, though that varies based on geography,” says Dr. Miller. “For example, fleas do not survive well in the Southwest. Environmental allergies are more common there.”

Food allergies are less common. When they do occur, these allergies are most often tied to a specific protein source, such as chicken or beef, rather than to a grain, like corn or rice.

Flea and food allergies are both fairly straightforward to treat. Got fleas? Control the fleas. Food allergy? Attempt to avoid that food.

Not Fleas or Food? Try Environmental

And that leaves the final category, allergies to environmental stimuli, which afflict between 10 and 20 percent of dogs. In fact, an environmental allergy—which includes allergy to grasses, pollens, insects, and more—is diagnosed only after ruling out all other possible causes of the allergic signs.

“In environmental allergies, the immune system overreacts to these allergens and causes a variety of signs, including itching, skin inflammation, skin infections, and ear infections,” says Dr. Miller.

Unfortunately, we cannot treat environmental allergies by removing grass, trees, dust, mold spores, and so on from our pet’s environment. So, instead of changing the pet’s environment, we have to mediate the pet’s allergic reaction.

“Immunotherapy, commonly known as ‘allergy shots,’ is one of the oldest and still most effective treatment options for environmental allergies in dogs,” says Dr. Miller. “It is the only natural way to truly try to change the immune system’s response to allergens, but it requires a long-term commitment on the part of the pet owner.”

How Immunotherapy Works

Immunotherapy is delivered by a specialist in veterinary dermatology working together with the pet’s general practice veterinarian to ensure continuity of care. Immunotherapy is a good choice for a dog that has not responded well to basic allergy medications or a dog that has frequent, severe allergic signs throughout the year.

“Overall, 60 to 80 percent of dogs with environmental allergy will respond very well to allergy shots, often eliminating the need for other medications the pet may have been given to control signs,” says Dr. Miller. “Young dogs may respond better to immunotherapy than do older dogs.”

Immunotherapy works by introducing small amounts of what the pet is allergic to and gradually increasing the dose over time, so that the pet builds a tolerance to these allergens. This is most often done via injections under the skin, but in some instances is completed via drops placed under the tongue, usually twice a day. Frequency of shots can vary, but most often they are given every other day initially and then decreased to once or twice weekly.

Immunotherapy must be continued for at least one year before effectiveness can be determined. During this first year, the pet will also take medication to control the allergic signs.

Skin Testing Identifies Allergens

As in human medicine, skin testing is used to identify an individualized formulation of allergens the animal reacts to. The dog is placed under sedation during skin testing. A trained veterinary dermatologist uses tiny needles to introduce small amounts of potential allergens under the skin. The dermatologist then watches for a skin reaction, indicating a positive allergy.

“Skin testing is the gold standard. Blood tests are also available, but reactions in the blood and the skin are not always the same. When investigating symptoms on the skin, we want to go directly to the skin to test reactions,” explains Dr. Miller.

Dr. Miller wants owners to understand that skin testing does not diagnose allergies. Testing is done only in the context of pursuing immunotherapy treatment. In some circumstances, a dog can be allergic yet have normal or negative allergy test results. This does not mean the dog is not allergic. Rather, it means that allergy shots are not a treatment option for that patient.

“After one year of shots, we start to wean the pet off the other allergy medication to see if any improvements have been made to the allergic signs. If there has been no change, we may stop giving shots and choose a different therapy. If the shots appear to be working, they may be continued for life,” explains Dr. Miller.

The goal of immunotherapy is to control the allergies, not to cure them. With proper treatment and owner education, many dogs with allergies can have perfectly normal, happy lives.

If you have questions about allergies and immunotherapy, contact your veterinarian or the veterinary dermatology service at the University of Illinois Veterinary Teaching Hospital.

By Hannah Beers

Featured photo by Thomas Hawk