Atopic Dermatitis or Pollen Wars: The Immune System Strikes Back!

Spring is a beautiful time of year here in the mountains, but April showers and May flowers also bring pollen. Human allergy symptoms usually include sneezing, stuffy nose, and itchy eyes, but dogs often show their allergies with itchy skin symptoms known as atopic dermatitis or atopy.

PetMD describes atopy this way: “Atopic dermatitis is an inflammatory, chronic skin disease associated with allergies. In fact, this is the second most common allergic skin disease in dogs. These allergic reactions can be brought on by normally harmless substances like grass, mold spores, house dust mites, and other environmental allergens.” There isn't a diagnostic test for atopic dermatitis, but there is a very typical pattern of itching. Dogs with atopy usually scratch, chew and/or lick their feet, face, chest, abdomen, and ears. For many years, dermatologists assumed that the allergens were inhaled and that the dog’s itch pattern was somewhat random. What we now realize is that a lot of the reaction is due to direct contact with the allergens on the skin, which makes a lot of sense when we look at where the itching occurs.

Contact with allergens is not the whole story for dogs with atopic dermatitis. The skin normally has several elements called the skin barrier that protect it from penetration by irritants, bacteria, and yeast. We know that genetics play a part in the development of allergic skin disease and the quality of the skin barrier. There can be abnormalities in the fat layer that forms part of the skin barrier, allowing irritants to migrate under the surface. Repeated exposure to allergens also increases the amount of work the skin barrier has to do. When the barrier breaks down, irritants can cross into the deeper layer of the skin where the immune system does its work. The immune response creates chemicals that further break down the skin barrier; you can see how the process becomes chronic and self-perpetuating.Atopy typically develops in dogs between 6 months and 6 years of age. It may be seasonal based on what is blooming or pollinating outside, or it may be year-round. There may be one main allergen involved, but over time many dogs will become sensitive to a large number of allergens. When the immune system gets “turned up” by allergens in the environment, it will often overreact to other irritants like flea bites or food ingredients. The damaged skin barrier also makes the skin more vulnerable to bacteria and yeast organisms to invade.

What can we do for these dogs?

  1. Remove allergens. This is the most important thing you can do if your dog shows any signs of itchy skin. Wipe your dog’s feet, face, and chest with a damp cloth whenever he’s been outside, even if it’s just to go to the bathroom. The less contact time the skin has with pollen and grass, the less opportunity there is for these irritants to break the barrier. If the atopy signs are year-round, your dog may be allergic to dust, dust mites, grain mites, or mold. Wash your dog’s bedding frequently, vacuum and dust mop frequently, and talk to your veterinarian about reducing mite exposure.
  2. Bathe frequently. Bathing is another way to remove allergens and add moisture to the skin. For routine baths, use a non-detergent moisturizing shampoo that does not have perfumes. During your dog’s itch season, weekly bathing is recommended. If your dog has a bacterial or yeast infection, your veterinarian will prescribe a medicated shampoo to reduce these organisms. If you have your dog bathed by a groomer, ask them to use a nonmedicated shampoo. If your veterinarian has prescribed a specific therapeutic product, take this product to the groomer each time.
  3. Topical moisturizers. Your veterinarian may also prescribe a moisturizing spray or cream rinse to apply onto the skin. Not all oils are beneficial to the skin, so ask before putting food oils (coconut oil, olive oil), human lotions, or mineral oil on the skin.
  4. Oral fatty acid supplements. Supplementing essential fatty acids in the diet can be very helpful in improving the skin barrier’s fat layer. The most beneficial fatty acids are found in fish oils. If you’ve ever shopped for fish oil products for yourself, you know that dosages can be very confusing. Animal Hospital of North Asheville sells a supplement called FreeForm, which has some of the highest amounts of essential fatty acids available. As noted above, there are a lot of food oils that do not provide skin benefits.
  5. Diet. Your veterinarian can help determine if a diet change might benefit your dog. Since food allergens can add more stimulation to an already charged-up immune system, a hypoallergenic diet may be recommended. Be aware that there are a LOT of diets on the market that advertise themselves as being good for the skin because they’re “grain-free,” or have certain ingredients in them.
  6. Medication. Sometimes we just need to stop the itching while we work on all of these other factors that contribute to atopy. Steroids have been used for a very long time for itch control, but is not recommended long-term. Fortunately, there are new products available like Apoquel and Cytopoint injections that are very targeted against the itch without suppressing the immune system or causing unwanted side effects. Secondary bacterial and yeast infections also must be treated with a combination of oral and topical medication.
  7. Allergy testing and immunotherapy. Allergy testing is not used to diagnose atopy. It is used to determine what dogs are allergic to. We are able to perform blood testing to measure antibody levels against a large variety of trees, grasses, weeds, molds, and mites. These tests are not 100% accurate but can help guide treatment. Allergy skin testing (like you might get at your allergist’s office) can be performed by a board-certified veterinary dermatologist. Immunotherapy is a process in which small amounts of allergen are given by injection or orally to try to train the immune system not to over-react to these substances. It is effective in about 60% of patients.

Probably the most important thing you can do is to have reasonable expectations. There is no cure for allergies! Dogs with atopy usually require lifelong management and a lot of diligent care by their owners. There is no “one treatment fits all” solution, but your veterinarian can help develop a plan to try to control the itch.