Why Is My Dog Chewing on His Skin & Pulling Out His Hair?

If your dog is chewing on his skin and pulling out his hair, he's probably suffering from some sort of allergy. While treatment depends on the actual allergen, all that chewing can cause secondary bacterial infections, for which your vet might have to prescribe antibiotics. Some allergies are relatively simple to treat, while others require trial and error to ease symptoms and manage your dog's condition.

Girl with pet dog in veterinarian's office
Your vet might conduct skin tests to determine the cause of your dog's allergy.
credit: XiXinXing/XiXinXing/Getty Images

Flea Allergy Dermatitis

If your dog isn't on flea preventive, his hair pulling and skin chewing might result from flea allergy dermatitis. If he's sensitive to flea bites, just one flea could cause all of that suffering. He's likely chewing areas in his mid-back, the base of his tail and hind legs, known in vet-speak as the "flea triangle." Fortunately, flea allergy dermatitis usually is cured by administering a monthly topical or oral flea preventive. Your vet can recommend the best product for your pet. While many flea preventives are available over the counter, your vet can provide you with a prescription product, Revolution, which also prevents heartworm infestation.

Contact Allergies

Canine atopic dermatitis often occurs seasonally, as the trigger is pollen, mold and grasses active at certain times of the year. Atopic dermatitis particularly affects the feet and face. Your dog also might suffer chronic ear infections. Through skin testing, your vet can determine what your dog is allergic to -- it's frequently more than one allergen. Treatment might include antihistamines or steroids to control itching, while medicated shampoos can make your dog feel better. Your vet might suggest immunization therapy, shots given over time that decrease your dog's sensitivity to the particular trigger.

Food Allergies

If flea allergy dermatitis is relatively easy to remedy, that's not necessarily the case with food allergies, which can cause similar symptoms. Dogs with food allergies chew or scratch anytime -- not just during flea season. Often, hair loss occurs on the back, tail and abdomen. Some dogs also experience persistent ear infections and gastrointestinal problems. Canines are often sensitive to dairy products, soy, beef, egg, chicken and wheat, according to the Michigan State University Veterinary Medical Center.

Food Elimination Trials

To get to the root of your dog's food allergy, your vet likely will conduct a food elimination trial. During this period, your dog can consume only a prescription diet or homemade food following specific recipes. That means no table scraps, treats, chew toys or any other type of food. Of course, your dog always must have water available. You'll gradually change your dog's current diet to the elimination diet over several days. After that, your dog eats nothing else for the next three months. You must keep a record of his activities during that time, including any chewing or hair pulling, but also his bowel movements and appetite. If he's itch-free at the end of the third month, you might continue the current diet. If not, your vet will put your dog on another elimination trial for the same period, a process continuing until you find the appropriate food for your pet.