A gastrointestinal ulcer in a dog can be treated with medication, diet, and rest.
Medications such as omeprazole or sucralfate can be prescribed to help heal the ulcer and prevent further damage. A bland diet may also be recommended, as well as avoiding food or activities that may aggravate the ulcer. Rest is important for the healing process, so your dog may need to stay calm and quiet for a few days.
If you think your dog may have a gastrointestinal ulcer, it's important to take them to the vet for an evaluation and proper treatment. With proper care, most ulcers will heal and your dog can return to their normal activities.