Atopic Dermatitis in Dogs

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 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 a veterinarian to pinpoint the exact allergens a 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 relief from allergies. In dogs that are only mildly affected, antihistamines or medicated shampoos may be effective. 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. Check with your veterinarian to determine the right course of treatment for your pet’s condition.

Steroid injections can provide immediate relief from itchy skin and inflammation. The relief is usually short-lived and lasts about two weeks. They can be useful in providing short-term relief while your veterinarian determines 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 works to block the itch. Apoquel is an oral medication that begins working within 4 hours. Monitoring bloodwork with long-term use of Apoquel is generally recommended.

In severely affected dogs, immunotherapy injections may be necessary. 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 diseases.

The prognosis for dogs affected by allergies is good, but it can require lifelong treatment to reduce clinical signs and ensure a good quality of life.

Common Causes of Skin Allergies in Pets

Below are three of the most common causes of allergic skin disease in pets.


The most common pet allergy is caused by fleas. Fleas are parasites that feed on a pet, and their saliva can trigger an allergic reaction, resulting in hair loss, redness, and intense itching. Hairless regions near the base of the tail are commonly seen in dogs and cats. Cats will sometimes experience hair loss around their chins as well. If your veterinarian suspects a flea allergy, he or she will check for evidence of live fleas and flea dirt. Your veterinarian will be able to make recommendations as far as an effective topical or oral flea preventative product as well as ways to rid the environment of fleas and their larvae. It can unfortunately take several months to resolve a flea infestation.


Another allergy we commonly see in pets is environmental. This is medically referred to as atopic dermatitis. Something in the environment, whether it is grass, pollen, dust, etc, causes a pet to become itchy after multiple exposures. Hairless regions or redness on the paws and inguinal regions are most common since these are the areas allergens touch when a pet is walking or laying down. These allergies can be a little more difficult to conquer. If further testing beyond a primary care veterinarian is necessary, a dermatologist can perform additional allergen testing and make treatment recommendations.


Some pets also develop food allergies after being on the same diet over time. These allergies develop as the body becomes sensitized from repeat exposure to a certain ingredient within the food. Typically the allergic component is the protein. Resolving a food allergy involves strict diet trials over several months. Recurrent ear infections can also be suggestive of possible underlying food allergies.

As always, if you notice changes to your pet’s skin or coat, it is best to schedule a veterinary visit to get to the bottom of it!