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Gastrointestinal Ulcers in Dogs

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An Australian Shepherd lays under a beige blanket on a cushion

Dr. Erica Irish author of Gastrointestinal Ulcers in Dogs

Most pet owners are aware of problems that can cause gastrointestinal disease in dogs. Intestinal parasites, toxin ingestions, and even getting into the trash can all cause symptoms such as vomiting, diarrhea, and lethargy.

Many of these causes can be detected thanks to a detailed medical history and sometimes lab work, but not all of these causes are easily identified.  

What Are The Gastrointestinal Ulcers in Dogs?

Ulcers form as a result of a defect in the protective mucosal layer that lines the inside of the stomach and the nearest part of the small intestines known as the duodenum. This layer is meant to protect the inner layers of the stomach and duodenum from the acids and digestive enzymes that are released by these organs. When ulcers form, acids and enzymes can destroy the inner layers, causing bleeding and severe pain in many cases. If the destruction of the inner layers is severe enough, it can lead to perforation of the organ, and the contents from the stomach or duodenum can cause a septic infection in the abdomen.

Symptoms of Gastrointestinal Ulcers in Dogs

The signs of gastrointestinal ulcers in dogs can be quite vague. When bleeding is involved, you may see red blood in your dog’s vomit or black colors in your dog’s stool. This dark color, referred to as melena, is an indication that there is bleeding from the upper part of the digestive tract. Other signs include:

  • Weakness or lethargy
  • Loss of appetite
  • Abdominal pain
  • Rapid heart rate or quick breathing
  • Pale gums or anemia

Causes of Gastrointestinal Ulcers

Gastrointestinal ulcers in dogs are similar to the type of ulcers that humans can develop, but the underlying cause for the ulcer is highly variable. In humans, studies show that certain bacteria (Helicobacter pylori) can cause ulcers, and factors like stress can lead to ulcers.

For dogs, much of what they ingest can impact the formation of ulcers. Non-steroidal anti-inflammatory drugs or NSAIDs can cause ulcers because they inhibit a certain enzyme. The kinds of NSAIDs made for dogs purposefully avoid this enzyme while human NSAIDs such as ibuprofen and naproxen are well-known to cause gastrointestinal ulcers. Foreign bodies (especially sharp or jagged ones) can cause physical damage to the mucosal layer, causing ulcers.

Strenuous exercise (like that of sled dogs and working) can cause ulcers; it is theorized that sustained elevated body temperatures will negatively impact the mucosal barrier in the stomach and duodenum. Liver disease can also increase the risk for ulcers, but the mechanism of action is unknown. Kidney disease can lead to ulcers because more acid is produced when dogs have kidney disease. Cancers of the stomach and intestines can also cause gastrointestinal ulcers because of the physical disruption of the mucosal layer due to tumor formation.

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Because of sometimes vague clinical signs, ulcers can be difficult to diagnose initially. Blood and urine testing may help to rule out underlying conditions such as liver and kidney disease, and it should be suspected if your dog has anemia with no discernible cause. X-rays can help look for signs of cancer, and ultrasound is a great tool to look for signs of bleeding or gastrointestinal perforation. Endoscopy is highly useful because a scope with a camera is used to look at the mucosal layer of the esophagus, stomach, and duodenum.  


The main goal of treatment is to address the underlying cause of your dog’s ulcers. If it is thought to be related to oral medication like NSAIDs, then your dog should stop taking these right away. If a human NSAID was ingested, your dog will likely need hospital care to prevent internal organ damage. Also, NSAIDs should never be mixed with oral steroids for dogs because there is a severe risk of ulceration with this combination. With liver or kidney disease, fluid therapy and various medications are often necessary.

Antacids like Tums have a very short half-life so these are not recommended. H2-antagonist medications like famotidine (Pepcid®) are very effective because they minimize the amount of stomach acid released. Proton pump inhibitors like omeprazole are even more effective because they completely block the release of stomach acid. If there is a concern for possible infection, antibiotics are sometimes prescribed, and cytoprotective medications like sucralfate can bind at ulcer sites to over some protection from further damage due to acids and enzymes.

If a severe ulcer has caused a gastrointestinal perforation, then surgery is necessary to close this opening. Without treatment in this situation, it can lead to sepsis and death.


Gastrointestinal ulcers can be very painful yet difficult to diagnose. Your vet will need to rule out several other factors, but regardless of cause, the therapies prescribed by most vets for GI upset can help in situations where ulcers have occurred. Advanced imaging is necessary to identify ulcers, but if these tests are cost-prohibitive, it is usually safe to try therapy with H2-antagonists or proton pump inhibitors. These are available in oral tablets and injectable varieties. Immediate therapy will always yield faster results!  

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Meet The Author 

Dr. Erica Irish author of Gastrointestinal Ulcers in Dogs

Dr. Erica Irish

Erica has worked in the veterinary field since 2006, starting out as a veterinary technician before graduating from the UF College of Veterinary Medicine in 2013. As a general practitioner in an animal hospital, she has many interests and is especially interested in dermatology, cardiology, internal and integrative medicine

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