Atopic Dermatitis in Dogs

I have been seeing numerous patients suffering from allergies recently. Environmental allergies are seasonal and occur most commonly in the spring and summer when there is an abundance of pollen and other allergens. This condition is medically referred to as atopic dermatitis.  

First, it is important to differentiate atopic dermatitis from food or flea allergies. To learn more about these other allergies, you may read my previous blog post. Atopic dermatitis usually affects a dog’s belly, paws, muzzle, or ears. Dogs suffering from this condition are usually brought to the animal hospital because they have started to itch, lose hair, or chew their paws. Additional presenting complaints may include watery eyes, sneezing episodes, or malodorous skin. Common environmental allergens are pollen, dust, molds, hay, and grass, among others.

There are specific tests available through your veterinarian to pinpoint the exact allergens your dog is sensitive to. One test is serological and consists of submitting a blood sample to detect antibodies against more than a dozen potential allergens. Intradermal skin testing is also an option, which consists of injecting a small volume of allergen within the skin and assessing whether any swelling or redness results.

Many treatment options are available to provide your dog relief from allergies. In dogs that are only mildly affected, antihistamines or medicated shampoos may be effective. Diphenhydramine (Benadryl), hydroxyzine, and cetirizine (Zyrtec) are all commonly prescribed antihistamines but be sure to get veterinary guidance before administering anything to your dog. These medications reduce the histamine response that occurs from allergies but must be administered frequently to maintain their effect. Medicated shampoos can have anti-inflammatory, anti-pruritic, and antimicrobial properties. Often, they are used in combination with another therapy.

Steroid injections can provide immediate relief from itchy skin and inflammation. The relief is usually short-lived and lasts about two weeks. Steroid injections should not be given repeatedly because they have a wide array of side effects. However, they can provide relief while you determine a long-term treatment strategy.

Two medications–Apoquel and Cytopoint— have been specifically formulated to combat allergies. Cytopoint is a subcutaneous injection that starts working within 24 hours and lasts 4-8 weeks. It is very safe and works to block a specific inflammatory cytokine involved in the itch pathway. Apoquel is an oral medication that also targets the itch pathway and begins working within 4 hours. Monitoring bloodwork with long-term use of Apoquel is recommended.

In severely affected dogs, immunotherapy injections may be recommended. They can provide long-term relief since they slowly build up tolerance to specific allergens. This therapy consists of a series of subcutaneous injections that each contain increased doses of the allergen. Injections are continued until an adequate dose is given to provide immunotolerance. This means your dog’s immune system will no longer react to the allergen causing issues. The goal of this therapy is similar to that of vaccines, which primes the immune system against certain disease.

The prognosis for dogs affected by allergies is good, but it can require lifelong treatment to reduce clinical signs and ensure your dog is comfortable.