Canine Atopy (Atopic Dermatitis)
Atopic dermatitis is a disease in which there is an inherited tendency to develop IgE antibodies in response to exposure to allergens that are inhaled or absorbed through the skin.
In early canine atopy, itching is seasonal and the skin looks normal. Dogs scratch at the ears and the underside of the body. The itching is often accompanied by face-rubbing, sneezing, a runny nose (known as allergic rhinitis), watery eyes, and licking at the paws (which may leave characteristic brown stains on the feet). In many dogs, the disease does not progress beyond this stage.
When it does progress, and itching-scratching cycle develops with deep scratches (called excoriations) in the skin, hair loss scabs, crusts, and secondary bacterial skin infection. These dogs are miserable. In time the skin becomes thick and darkly pigmented.
A secondary dry or greasy seborrhea with flaky skin often develops in conjunction with the skin infection.
Ear canal infections may accompany these signs, or may be the sole manifestation of atopy. The ear flaps are red and inflamed, and the canals are filled with brown wax that eventually causes bacterial or yeast otitis.
Allergens in the environment begin this cyclical condition. Itching and scratching can perpetuate the condition and lead to secondary bacterial infection.
Canine atopy, especially when complicated by pyoderma, can be difficult to distinguish from flea allergy dermatitis, scabies, demodectic mange, food allergies, and other skin diseases. The diagnosis can be suspected based on the history, location of skin lesions, and seasonal pattern of occurrence. Skin scrapings, bacterial and fungal cultures, skin biopsy, and a trial hypoallergenic test diet should be considered before embarking on an involved course of treatment for atopy. It is important to eliminate fleas. The majority of dogs whit canine atopy are allergic to fleas and may have an associated flea allergy dermatitis complicating the picture.
The preferred method of diagnosing canine atopy is through intradermal skin testing, which means injecting small amounts of may known allergens and observing the skin reaction. This can be time consuming and expensive since it will require many trips to the vet. To be accurate, all supportive drugs must be withdrawn during the testing period.
If intradermal skin testing is not available, a serologic blood test (ELISA) designed to detect group-specific IgE antibody may assist in making the diagnosis.
The most effective long-term solution is to change the dog's living situation to avoid the allergen. The atopic dog is usually allergic to many different allergens, and it may not be possible to completely avoid exposure.
Most dogs with atopy respond well to treatment. A first and most important step is to reduce the threshold for scratching by treating and eliminating all associated irritative skin problems, such as fleas, seborrhea, and pyoderma.
Antihistamines control itching and scratching in 20 - 40% of atopic dogs. Corticosteroids are the most effective anti-itch drugs, but also have the most serious side effects. They are best used intermittently in low doses and for a limited time. Preparations containing hydrocortisone with Pramoxine are often prescribed for treating local areas of itching. Pramoxine is a topical anesthetic that provides temporary relief from pain and itching.
Derm Caps and other essential omega-3 fatty acid products derived from fish oils have produced good results in some dogs. They are used as nutritional supplements in conjunction with other therapies. A variety of shampoos are available and may be prescribed by your vet to rehydrate the skin, treat bacterial infection, and control seborrhea.
Dogs who do not respond to medical treatment can be considered for immunotherapy with hyposensitization. This involved skin testing to identify the allergen(s) and then desensitizing the dog to the specific irritants through a series of injections given over a period of 9 - 12 months or longer. Some dogs will require periodic boosters during times when allergens are heavy.
Wipe the dog when when she comes in from outdoors, which will help to remove the pollens picked up in the coat.
Some dogs with atopy benefit from switching to a higher quality dog food even if they don't have a food allergy. Research brands such as Innova, EVO, Eagle Pack & Wellness (now Wellpet), Fromm, Canidae, and other specialty store only brands.
If they are allergic to house dust mites, they often cross-react with grain mites and will benefit from a canned food or dry food that is grain free (EVO).
Please contact your veterinarian if you think your pet may have this condition.
Show Sources & Contributors +
Publisher: BowTie Press, 2005
Authors: Kristin Meuh-Roe, Jarelle S. Stein
Dog Owners Home Veterinary Handbook
Publisher: Wiley Publishing, 2007
Authors: Debra M. Eldredge, Liisa D. Carlson, Delbert G. Carlson, James M. Giffen MD