By Ann Hohenhaus, DVM
The summer of 2012 will go down in my personal history book as the summer of allergies. Not for me, but for my canine patients. I have received many frantic calls from my cancer patients’ families concerned that their beloved pet’s cancer has returned. After a check-up with me at The Animal Medical Center, I have reassured them the cancer continues to be in remission, but their allergies are way out of control.
Today, the preferred term for allergies to things in the environment, like house dust mites pollen, mold, trees and grasses, fleas, and even your unsuspecting household cat, is allergic dermatitis. Allergic dermatitis is also known as atopy, allergic inhalant dermatitis, seasonal allergy, or environmental allergy. Whatever it’s called, the manifestation is red skin, “hot spots,” ear infections, recurrent skin infections and scratching like mad. The development of allergic dermatitis requires two things: a dog with a genetic predisposition to developing allergies and an allergen in the environment to incite the allergic response. Allergic dermatitis is a complicated disease and often requires complicated therapy.
At least three mechanisms play a role in allergic dermatitis in dogs. First, the environmental allergen causes the release of histamine from a cell known as a mast cell, which sets off an allergic reaction. T-cells have a yin-yang effect on the immune system, both ramping up the immune system and blocking a protective effect against allergies. Finally, normal skin protects the body from invasion by allergens. Dogs suffering from allergic dermatitis likely have impaired function of the skin cells, allowing allergens access and predisposing your dog to yeast and bacterial infections.
The net effect of all this cellular hysteria: an itchy dog.
Complex treatment regimen
Given the complexities described in the pathways leading to allergic dermatitis, you should not be surprised to receive a small pharmacy’s worth of prescriptions when your dog is diagnosed with allergic dermatitis. What follows is a brief description of some of the more common medications used to treat allergic dermatitis.
1. Although the role of histamine is limited in canine allergic dermatitis, antihistamines, if they decrease itchiness, are very safe and cost effective.
2. Shampoos play multiple roles in the management of allergic dermatitis. Bathing your dog is soothing to the skin and decreases surface allergens, and medicated shampoos decrease surface bacteria and yeast. Hopefully, new shampoos will be developed to help augment the lost barrier function of the skin.
3. Antibiotics and anti-yeast medications are critical in controlling secondary infections in the skin of itchy dogs. The function of deregulated T-cells can be modified by the use of immunosuppressive agents, most commonly steroids, and more recently cyclosporine.
4. Finally, dogs can get allergy shots, a form of immunotherapy where the immune system is gradually desensitized to the offending allergen. For several of my patients, this form of treatment has dramatically improved their quality of life by decreasing their itchiness and skin and ear infections.
What a pet owner can do
If your dog is scratching, as are many of my patients, see your veterinarian. When my itchy dog patients need more specialized skill than I have to manage their allergic dermatitis, I refer them to a dermatology specialist. You can find a board certified dermatologist on the American College of Veterinary Dermatology website.
I hope one or more of the treatments I have described can help make your dog more comfortable in these waning summer months.