Chewing on feet and hind legs is a classic sign of allergies in dogs. Flea allergies –The most common allergy dogs experience is a reaction to flea bites, called flea allergy dermatitis. Even if your dog is protected against fleas by a collar or treatment, one flea can secrete enough saliva in a bite to cause itching and discomfort. Food or shampoo – Dogs can also be allergic to ingredients in their food or shampoo. Pollen – They can even have reactions to some of the same things that cause human hay fever: pollen, dust, mold and grasses. Contact your veterinarian – Your veterinarian can help you determine if your dog is being bothered by one of these allergies or if there is another underlying medical issue causing this behavior. If it is a food allergy, you may be able to simply change your dog’s diet. Other allergies can be treated with an antihistamine or steroid prescription.