Dogs can develop allergies to specific components of a diet at any age, regardless of the quality of the food they are fed. Most often, dogs are allergic to protein sources in the diet, such as beef, chicken, or pork. Dogs with food allergies will have itchy skin and/or itchy ears year-round. The only way to diagnose food allergies is to complete a food trial. A food trial involves feeding a prescription hypoallergenic diet, such as Hill’s z/d, for a 3-month period to assess for improvement or resolution of signs. During a food trial, the ONLY food your dog should receive is the prescription diet, as treats or table scraps can interfere with the trial. If the prescription diet helps provide relief from itching, it should be fed for the rest of your dog’s life.