Stomach Ulcers in Dogs

Stomach ulcers in dogs are open sores or erosions in the lining of the stomach, and sometimes the first part of the small intestine. Your vet may call this gastroduodenal ulceration or erosion. These lesions develop when the protective lining of the digestive tract is damaged or when acid, digestive chemicals, poor blood flow, inflammation, or certain medications overwhelm the stomach’s normal defenses.

Some dogs have mild irritation at first, while others develop bleeding ulcers that cause vomiting, weakness, or black stool. In more serious cases, an ulcer can perforate, meaning it creates a hole in the stomach or intestinal wall. That can lead to peritonitis, shock, and a true emergency. Because the signs overlap with many other digestive problems, stomach ulcers should never be diagnosed at home.

Ulcers are usually a symptom of an underlying problem rather than a stand-alone disease. NSAID pain relievers are a well-known cause, but they are not the only one. Kidney disease, liver disease, severe stress on the body, heat stroke, major trauma, mast cell tumors, gastrin-secreting tumors, and some toxins can all play a role. Dogs with chronic vomiting, poor appetite, or unexplained anemia may need a workup to look for ulcer disease.

The good news is that many dogs recover well when the ulcer is found early and the underlying cause is addressed. Treatment can range from outpatient medication and diet changes to hospitalization, transfusion support, endoscopy, or surgery. The right plan depends on how sick the dog is, whether bleeding is present, and what your vet finds during testing.

Diagnosis starts with a careful history and physical exam. Your vet will want to know about vomiting, stool color, appetite, recent medications, toxin exposure, and any history of kidney disease, liver disease, cancer, or endocrine disease. Be sure to mention all pain relievers, steroids, supplements, and over-the-counter products, because some medications can increase ulcer risk or worsen bleeding.

Initial testing often includes a complete blood count, chemistry panel, and urinalysis. These tests help your vet look for anemia from blood loss, dehydration, infection, kidney or liver problems, and other illnesses that can either cause ulcers or make them harder to heal. Fecal testing may also be recommended, especially if parasites or other intestinal disease are possible.

Imaging may include abdominal X-rays or ultrasound. These tests do not always show an ulcer directly, but they can help rule out foreign bodies, masses, perforation, fluid in the abdomen, or other causes of vomiting and pain. In some dogs, endoscopy is the most useful next step. This procedure uses a flexible camera under anesthesia to inspect the stomach and upper small intestine and may allow your vet to collect biopsies.

Because ulcers are often secondary to another disease, diagnosis is really about two goals at once: confirming the ulcer and finding the reason it formed. That may mean additional testing for tumors, clotting problems, Addison’s disease, severe inflammation, or organ dysfunction. The treatment plan is strongest when both the ulcer and the root cause are addressed.

One of the best-known causes of stomach ulcers in dogs is medication, especially nonsteroidal anti-inflammatory drugs, or NSAIDs. These drugs can reduce the stomach’s protective mechanisms, particularly if they are overdosed, combined with steroids, or used in a dog with dehydration or underlying illness. Corticosteroids may also contribute, especially when paired with NSAIDs. This is why pet parents should never mix pain medications or give human products unless your vet specifically says to do so.

Ulcers can also develop when the body is under major stress or when blood flow to the stomach lining is reduced. Severe trauma, shock, sepsis, heat stroke, major surgery, and critical illness can all set the stage for ulcer formation. Dogs with kidney disease, liver disease, or some endocrine disorders may be at higher risk as well. In these cases, the ulcer is part of a bigger medical picture.

Certain cancers are another important cause. Mast cell tumors can increase histamine release, which may increase stomach acid and ulcer risk. Gastrin-secreting tumors are less common but can also lead to severe ulceration. Foreign bodies, toxins, caustic substances, and chronic inflammatory disease may damage the stomach lining directly. Helicobacter organisms can be found in some dogs, but their role in canine ulcer disease is less clear than it is in people.

Risk rises when several factors overlap. For example, an older dog with arthritis taking an NSAID, mild kidney disease, and poor appetite may be more vulnerable than a healthy young dog on a short medication course. That is why your vet looks at the whole patient, not only the stomach signs, when deciding how concerned to be and what tests matter most.

Not every stomach ulcer can be prevented, because some are linked to serious internal disease. Still, there are practical ways to lower risk. The biggest one is medication safety. Give NSAIDs, steroids, and other prescription drugs exactly as directed, and never combine them unless your vet has specifically approved that plan. Human pain relievers can be especially dangerous for dogs.

Routine monitoring matters for dogs on long-term medication or dogs with chronic kidney, liver, or endocrine disease. Recheck exams and lab work help your vet catch side effects early and adjust treatment before stomach injury becomes severe. If your dog starts vomiting, eating less, or acting painful while on medication, contact your vet promptly instead of waiting to see if it passes.

Good prevention also means limiting access to toxins, caustic substances, garbage, and foreign objects. Dogs that raid the trash, chew bottles, or swallow nonfood items are at risk for many digestive injuries, including ulceration. Keeping medications, cleaners, and toxic plants out of reach is part of the same plan.

For dogs with a history of ulcers, prevention may include a more cautious medication strategy, GI-friendly diet choices, and faster follow-up when stomach signs return. Some dogs need preventive stomach medication during high-risk periods, but that decision should come from your vet based on the dog’s history and current health.

Prognosis depends less on the ulcer itself and more on the cause, the amount of bleeding, and whether complications are present. Dogs with mild to moderate ulcers that are treated early often do well, especially when the trigger is identified and removed. Many uncomplicated cases begin to improve within several days of treatment, though full healing can take longer and follow-up is important.

Recovery is more guarded when ulcers are linked to cancer, severe organ disease, shock, or a perforation. A perforated ulcer can spill stomach contents into the abdomen and cause life-threatening infection and inflammation. Dogs with major blood loss may need transfusion support, and dogs with tumors or systemic disease may need a longer and more complex treatment plan.

At home, recovery usually involves medication on schedule, diet instructions from your vet, and close monitoring for vomiting, black stool, weakness, or poor appetite. Some dogs need repeat bloodwork to make sure anemia is improving and organ values are stable. If endoscopy or surgery was needed, your vet may also recommend activity restriction and recheck imaging or biopsy review.

Even after recovery, recurrence is possible if the underlying problem returns or if ulcer-triggering medication is used again. That does not mean every dog will have chronic trouble. It means the long-term plan should be individualized, with your vet balancing symptom control, medication needs, and the dog’s overall health picture.