A common sign or symptom of dogs with a food allergy is itching – usually around the feet or paws or on the face or the ears. As a veterinarian, one thing I will look for are ear infections, which are very common or secondary elements of a food allergy. Some other symptoms you may observe are vomiting, diarrhea, or indigestion. If you're seeing any of those signs, it’s an alert that your dog may have some kind of food sensitivity.