Atopy, or atopic dermatitis, is one of the most common skin diseases of dogs and it is estimated to affect between 3% and 15% of dogs.  Atopy rarely afflicts cats. An animal with atopy often becomes hypersensitive to inhaled allergens such as pollens, dander, grasses, mold, and dust. Atopy is usually first noticed in younger dogs, between 10 months to 3 years. Unfortunately, these pets are usually plagued by skin problems for life

Canine atopic dermatitis occurs in two stages. The first stage is the sensitization phase when the allergens are first absorbed into the skin. In the second stage, exposure to the same allergen causes a reaction resulting skin inflammation, dermatitis and itching.  As long as the animal is exposed to the allergen, it will have problems.  Allergens that dogs can be hypersensitive to include  mold, dust, grass, trees, insects, and proteins found in food.

Signs of Atopy

• Generalized scratching and itching

• Redness of skin

• Hair loss from repeated biting, licking, chewing and scratching

• Skin rash, infections, and irritation

• Unusual odor

• Skin thickening and pigment changes

• Ear infections

• Dandruff (scales and crusting)

Diagnosis

There is no simple test to diagnose atopy. It is diagnosed by comparing the patient’s history and the results of examinations and medical tests. A veterinarian will also rule out other causes for dermatitis, such as skin mites or food allergies.

Treatment

Atopic dermatitis is usually a life-long disease. It often becomes worse as the animal ages, especially if the pet has not received proper treatment. Most animals develop secondary issues, such as bacterial or fungal skin infections, bald patches, sores, and thickened skin,  that also need treatment. To complicate things even further, some animals may become resistant to medical therapy.

Removing allergens from environment:

The first step to helping your pet is to remove as much of the allergens from the environment as possible. For example, if the veterinarian determines that your dog has a flea allergy, then you should take all appropriate steps to keep fleas away from the pet. Likewise, if your animal has a dust mite allergy, one should make its environment as clean and dust free as possible. 

Symptomatic care

Corticosteroids-- like Prednisone or Hydrocortisone, are often used as the first line of defense against itchy skin. These medications are given through injection, orally, or and even as topical ointments. They can provide immediate relief, but may have undesirable side effects, such as increased appetite, thirst and urination. Repeated use of cortisone therapy can put your pet at risk of developing diabetes and  disease called Cushing's Disease, so it is usually used as a last resort.

Antihistamines – like Diphenhydramine, have relatively few side effects compared to cortisones, although many pets will not respond to them alone.

Fatty Acid Supplements - Special fatty acid supplements may help stop inflammation of the skin, and are often used in combination with other medications.

Topical treatments – Medicated shampoos and ointments can give your pet itch relief or help with secondary conditions such as fungal infections and scaling. Treatment should be repeated frequently for best results.

Allergy Testing and Immunotherapy

Allergy testing helps identify the specific allergens that the dog is allergic. There are two types of tests, an intradermal test and a serum allergy test.

With intradermal tests, the veterinarian injects various potential allergens into the skin, then monitors these areas for an allergic response.  Before the pet can have the Intradermal Test, he has to be taken off medication that helps give him allergy relief for several weeks, because it will interfere with the test results. This can be quite uncomfortable for the pet, but necessary for accurate results.