Gastrointestinal Ulcers in Dogs

See your vet immediately if you think your dog may have a gastrointestinal ulcer. These ulcers are open sores that form when the protective lining of the stomach or upper small intestine breaks down. Once that barrier is damaged, acid, digestive enzymes, and bile can injure deeper tissue. Some ulcers bleed slowly, while others cause sudden bleeding, severe pain, or even a hole in the stomach or intestine.

In dogs, gastrointestinal ulcers are usually a complication of another problem rather than a disease that appears on its own. Common examples include nonsteroidal anti-inflammatory drugs, certain toxins, severe systemic illness, liver disease, kidney disease, and some cancers. Because the signs can overlap with gastritis, foreign body obstruction, pancreatitis, and other digestive emergencies, your vet usually needs testing to confirm what is going on.

The outlook varies with the cause and how early treatment starts. Mild, uncomplicated ulcers may improve within days once the trigger is removed and supportive care begins. Bleeding ulcers, perforated ulcers, or ulcers linked to cancer or organ disease are more serious and may require hospitalization or surgery. Early veterinary care can make a major difference in recovery.

Diagnosis starts with a careful history and physical exam. Your vet will want to know about recent medications, especially NSAIDs or steroids, possible toxin exposure, appetite changes, vomiting, stool color, and any existing liver, kidney, endocrine, or cancer diagnosis. On exam, your vet may look for dehydration, abdominal pain, pale gums, fever, weakness, or signs of shock.

Testing often includes a complete blood count, chemistry panel, and urinalysis. These tests can help detect anemia from blood loss and look for underlying disease such as kidney injury, liver disease, or Addison’s disease. Fecal testing may be recommended to rule out parasites or other causes of GI signs. Abdominal X-rays or ultrasound can help look for foreign material, masses, thickened stomach or intestinal walls, or evidence of perforation.

Endoscopy is one of the most direct ways to confirm an ulcer because it lets your vet visualize the lining of the esophagus, stomach, and upper small intestine. In some cases, biopsies are taken during the procedure to look for inflammation, infection, or cancer. Not every dog needs endoscopy right away, but it can be very helpful when signs are ongoing, bleeding is recurrent, or the underlying cause is unclear.

In dogs, gastrointestinal ulcers usually happen when the stomach or intestinal lining loses its normal protection. Merck notes that NSAID administration, neoplasia, and hepatic disease are among the most commonly reported causes of gastroduodenal ulceration or perforation in dogs. Human pain relievers such as ibuprofen and naproxen are especially dangerous and can cause ulceration and bleeding, while even veterinary NSAIDs can create risk in some dogs if dosing, hydration, or concurrent disease becomes a problem.

Other possible causes include kidney disease, severe liver disease, shock, sepsis, pancreatitis, foreign bodies, mast cell tumors, gastrin-secreting tumors, and some toxic exposures. Corticosteroids are a more controversial cause on their own, but they can increase concern when combined with NSAIDs or when a dog is already medically fragile. Dogs with serious systemic illness may develop ulcers because blood flow to the GI lining is reduced or because acid and protective mucus become imbalanced.

Risk also rises when a dog has repeated vomiting, poor circulation, major trauma, or cancer affecting the digestive tract. In some cases, ulcers are secondary to a hidden disease that has not yet been diagnosed. That is why treatment is not only about reducing stomach acid. Your vet also has to look for the reason the ulcer formed in the first place.

Prevention starts with medication safety. Never give human pain relievers like ibuprofen or naproxen unless your vet specifically instructs you to do so, because these drugs can cause GI ulceration and bleeding in dogs. Even prescription veterinary NSAIDs should only be used exactly as directed, and your vet may recommend monitoring bloodwork for dogs on longer-term treatment or for dogs with kidney, liver, or other chronic disease.

It also helps to reduce access to toxins and foreign materials. Keep medications, supplements, topical creams, batteries, and other household hazards secured. If your dog has a chronic illness such as kidney disease, liver disease, or cancer, regular follow-up visits matter because managing the underlying condition may lower ulcer risk. Tell your vet promptly if your dog develops vomiting, dark stool, appetite loss, or lethargy while taking any medication.

Some dogs with a history of ulcers may need a more tailored prevention plan. That can include diet changes, avoiding certain drug combinations, using GI-protective medication when appropriate, and closer monitoring during stressful illness or surgery. Prevention is not one-size-fits-all, so the safest plan is the one your vet builds around your dog’s health history.

The prognosis for gastrointestinal ulcers in dogs depends on the cause, how much bleeding has occurred, and whether the ulcer has perforated. For uncomplicated ulcers, the outlook is often good once the trigger is removed and treatment starts. PetMD notes that many less complicated ulcers begin showing improvement within about 5 to 7 days, although full healing can take longer and follow-up care still matters.

Recovery is more guarded when ulcers are linked to cancer, severe liver disease, kidney failure, shock, or a perforation into the abdomen. A perforated ulcer can lead to peritonitis, which is a life-threatening emergency. Dogs with major blood loss may need transfusion support, and dogs with ongoing vomiting or poor appetite may need hospitalization until they can stay hydrated and keep medications down.

At home, your role is to give medications exactly as prescribed, feed the diet your vet recommends, and watch closely for relapse. Call your vet right away if you see black stool, vomiting blood, worsening weakness, pale gums, or renewed abdominal pain. Some dogs recover fully and never have another ulcer, while others need long-term management because the underlying disease is still present.