Stomach Ulcers in Dogs: Symptoms, Causes, and Treatment

Name: Stomach Ulcers in Dogs: Symptoms, Causes, and Treatment
Creator: Dr. Zubair Khalid

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-10-03

Stomach ulcers in dogs are open sores in the protective lining of the stomach or upper intestine. They can cause vomiting, appetite loss, and dark tarry stool, but early signs are often vague. Knowing the signs of dog ulcer problems helps you act before the condition becomes an emergency.

This article is educational and is not a substitute for veterinary diagnosis or treatment.

Quick Answer

The most telling signs are vomiting (sometimes with blood), black tarry stool, a painful or tense belly, and a sudden drop in appetite.
Common causes include NSAID pain medications, steroids, tumors, liver disease, and severe stress or illness [1][2].
Ulcers are diagnosed with bloodwork, ultrasound, or endoscopy, which is the gold standard [3].
Treatment centers on acid-suppressing drugs called proton pump inhibitors, plus removing the underlying cause [3].
Any dog with black stool, vomiting blood, or a swollen painful abdomen needs to be seen right away.

What Dog Stomach Ulcer Symptoms Look Like

A stomach ulcer is a break in the stomach lining. The stomach normally protects itself from its own acid and digestive enzymes, but when that barrier fails, acid and pepsin (a digestive enzyme) make the damage worse [4]. The result is an open sore that can bleed, hurt, and interfere with normal eating.

The tricky part is that dog ulcer signs are often vague. In one review of the condition, clinical signs were described as usually nonspecific, meaning many dogs simply seem "off" before anything dramatic happens [3].

Signs You Might Notice at Home

Vomiting, which may happen after meals or on an empty stomach
Vomiting material that looks like coffee grounds or contains fresh blood
Black, tarry, or unusually foul-smelling stool (digested blood)
Reduced appetite or refusing food
Weight loss over weeks
A belly that feels tense or hurts when touched
Lip smacking, drooling, or gulping (signs of nausea)
Pale gums if bleeding has been ongoing
Weakness or lethargy

Vomiting blood (hematemesis) and black stool (melena) are the classic bleeding signs, but they do not appear in every dog [3]. A dog can have a serious ulcer and never vomit blood. That is one reason ulcers are easy to miss early.

What Is Normal and What Is Not

Occasional vomiting in dogs is common. A single episode in an otherwise bright, playful dog that eats normally the next day is usually not an ulcer. What raises concern is a pattern: repeated vomiting over days, vomiting that keeps happening after meals, a dog that stops eating, or any change in stool color to black or tarry.

A swollen or distended abdomen is a separate warning sign that can point to several serious problems. If your dog's belly looks bloated or feels tight, see Dog Swollen Stomach Symptoms and Dog Swollen Stomach Causes for more detail.

Main Causes of Stomach Ulcers in Dogs

Ulcers form when something damages the stomach lining or drives up acid production [4]. Several conditions are linked to gastroduodenal ulceration or erosion (GUE) in dogs. A large case review of 168 dogs with confirmed GUE found clear associations with certain drugs and diseases [1].

Cause	Typical clues	How urgent
NSAID pain medications	Recent or ongoing use of carprofen, meloxicam, or similar drugs, often at high dose or with steroids	Urgent, stop the drug only under vet guidance
Glucocorticoids (steroids)	Long-term prednisone or similar, often for allergies or immune disease	Urgent, call your vet
Gastrointestinal tumors	Older dog, weight loss, chronic vomiting, poor response to treatment	Urgent, needs imaging
Liver disease	Known liver problem, jaundice, abnormal liver values	Urgent, needs workup
Severe illness or stress	Hospitalization, major surgery, shock, critical illness	Emergency if bleeding signs appear
Foreign body or toxin	Sudden onset, possible ingestion, drooling, retching	Emergency

NSAID administration was the strongest drug-related factor in that study, linked to roughly six times higher odds of GUE [1]. Glucocorticoid (steroid) administration was also significantly associated, at about three times higher odds [1]. Gastrointestinal neoplasia (tumors) carried the highest association of all, at more than thirteen times higher odds [1].

Liver disease is often listed as a cause of gastroduodenal ulceration in dogs. A study of 40 dogs with confirmed liver disease found ulcers or erosions in 4 of them, about 10 percent [2]. So the link is real but does not affect every dog with liver disease.

Stress deserves a mention too. In horses, a similar condition called equine gastric ulcer syndrome is closely tied to physical and psychological stressors [5]. The same principle is widely accepted in dogs: serious illness, pain, and stress can contribute to stomach lining damage, though the exact role of stress alone in dogs is not well established in veterinary research.

Red Flags That Mean Emergency

Some signs mean you should stop reading and call an emergency clinic now.

Vomiting blood or material that looks like coffee grounds
Black, tarry stool
A belly that is swollen, hard, or painful to touch
Collapse, weakness, or pale gums
Unproductive retching with a bloated abdomen (possible bloat or gastric dilation)
Known ingestion of a toxin, human medication, or foreign object

Bleeding ulcers can cause significant blood loss. A dog with a swollen, painful abdomen may have a problem that needs immediate decompression, and treatment success depends on prompt diagnosis and care by a veterinarian [4]. If your dog's stomach looks swollen for any reason, review What Would Cause A Dogs Stomach To Swell so you can describe what you are seeing when you call.

Safe Things You Can Do at Home While Waiting

Home care for a suspected ulcer is mostly about avoiding harm and getting ready for the vet visit.

Stop giving any NSAID or steroid unless your veterinarian tells you otherwise. Do not restart it on your own.
Do not give human pain relievers. Many are toxic to dogs, and some make ulcers worse.
Offer small amounts of bland food if your dog will eat, but do not force food or water.
Keep a written log of vomiting times, stool color, appetite, and any medications given.
Save a photo of any vomit or stool that looks abnormal. It helps your vet.
Keep your dog calm and confined. Stress and activity can worsen bleeding.
Call your veterinarian or an emergency clinic for guidance before giving anything by mouth.

Never give over-the-counter acid reducers, antacids, or pain pills without veterinary direction. Doses for dogs are calculated by your veterinarian based on your pet's weight and health, and some human products contain ingredients that are unsafe for dogs.

What Your Veterinarian Will Check and Test

Your vet starts with a full history. Bring the medication list, including doses and how long your dog has taken each drug. Drug history is one of the strongest clues because NSAIDs and steroids are leading causes [1].

Physical Exam

Your vet will check hydration, gum color, belly tenderness, and signs of shock. They may press gently on the abdomen to look for pain or a mass.

Blood and Stool Tests

Bloodwork checks for anemia (which suggests bleeding), organ function, and dehydration. A stool test can confirm digested blood. These tests help rule out other causes of vomiting and weight loss.

Imaging

Abdominal ultrasound can show changes consistent with ulceration, though it cannot always confirm an ulcer directly [3]. Ultrasound is also useful for spotting tumors, liver changes, and other organ problems.

Endoscopy

Endoscopy (passing a camera into the stomach) is considered the gold standard for diagnosing ulcers [3]. It lets your vet see the sore directly and take biopsy samples. Endoscopy requires anesthesia, so it is usually reserved for dogs where the answer will change treatment.

For a deeper look at how ulcers are confirmed and managed, see Canine Gastric Ulceration: Diagnosis and Management.

Treatment Basics

Proton pump inhibitors are the treatment of choice for gastrointestinal ulcers in small animals [3]. These drugs reduce stomach acid so the lining can heal. Your vet may also treat the underlying cause, such as stopping a medication, managing liver disease, or removing a tumor. Some dogs need fluids, blood products, or a feeding tube if they are severely ill.

Preventing Ulcers and Monitoring Dogs at Risk

Prevention focuses on the causes you can control.

Use NSAIDs only as prescribed. Never combine them with steroids unless your vet specifically plans for it, since both raise ulcer risk [1].
Ask about stomach protection. If your dog needs long-term NSAIDs or steroids, ask whether a proton pump inhibitor or other protective drug is appropriate.
Monitor for early signs. Watch for appetite changes, vomiting, or dark stool in any dog on long-term medication.
Keep routine bloodwork. Dogs on chronic medication or with liver disease benefit from regular monitoring.
Manage stress during illness or hospitalization. Ask your vet how they reduce stress for dogs recovering from major illness or surgery.
Do not use leftover medications. Old prescriptions and doses meant for another pet can cause harm.

One more note on long-term acid suppression: chronic omeprazole use has been linked to gastric mucosal changes in dogs, including thickened folds seen on ultrasound [6]. In one reported case, long-term omeprazole use in a dog was associated with fundic gland polyps that resolved after the drug was stopped [7]. This does not mean the drug is unsafe when needed. It means long-term use should be a deliberate decision with your veterinarian, not an indefinite habit.

If you notice skin wounds or sores elsewhere on your dog, those are a different problem. See Dog Skin Ulcers: Causes, Treatment, and When to See a Vet for that topic.

Limitations and When to Contact a Veterinarian

Stomach ulcers in dogs can be mild or life threatening, and the signs overlap with many other conditions. No article can tell you which one your dog has. Individual cases need a veterinarian who can examine your dog, review medications, and run tests.

Contact your veterinarian the same day if your dog has repeated vomiting, refuses food for more than a day, has a known NSAID or steroid exposure, or has any change in stool color.

Go to an emergency clinic now if you see vomiting blood, black tarry stool, collapse, pale gums, a hard or swollen belly, or unproductive retching.

Schedule a routine visit if your dog has chronic intermittent vomiting, gradual weight loss, or you want to review long-term medication risks. Early diagnosis and treatment give the best chance of a good outcome [4].

Frequently Asked Questions

Can a dog have a stomach ulcer without vomiting?

Yes, some dogs with ulcers show only vague signs like appetite loss, lethargy, or weight change. Clinical signs are often nonspecific, and bleeding signs like vomiting blood or black stool do not appear in every case [3]. If your dog seems unwell for more than a day or two, a vet visit is reasonable.

Are NSAIDs the most common cause of ulcers in dogs?

NSAIDs are one of the strongest and most consistent risk factors identified in dogs with confirmed gastroduodenal ulceration [1]. Steroids and gastrointestinal tumors are also strongly linked [1]. That said, many dogs take NSAIDs safely, and risk depends on dose, duration, other drugs, and your dog's overall health.

How long does it take for a dog stomach ulcer to heal?

Healing time varies with the cause, the size of the ulcer, and how well the underlying problem is controlled. Your veterinarian will set a recheck schedule and may repeat imaging or bloodwork. Do not stop acid-suppressing medication early just because your dog seems better.

Can stress alone cause a stomach ulcer in a dog?

Stress is widely believed to contribute to stomach lining damage, and in horses, stress is closely tied to gastric ulcer disease [5]. In dogs, the role of stress by itself is not well established in veterinary research. Stress is more likely to be one factor among several, especially during serious illness or hospitalization.

Is long-term omeprazole safe for my dog?

Proton pump inhibitors are the treatment of choice for ulcers, and many dogs need them for weeks or longer [3]. However, long-term use has been linked to gastric mucosal changes and, in one reported case, fundic gland polyps that resolved after the drug was stopped [7]. Your veterinarian will weigh the benefit against the risk and decide how long your dog should stay on it.

References

Medical conditions associated with gastroduodenal ulceration or erosion in 168 dogs: 2008-2018. Journal of veterinary internal medicine, 2021.
Gastroduodenal ulceration in dogs with liver disease. Journal of veterinary internal medicine, 2022.
Gastrointestinal Ulcers in Small Animals - Digestive System. Merck Veterinary Manual.
Disorders of the Stomach and Intestines in Dogs - Dog Owners. Merck Veterinary Manual.
Incorporating a Behavioral Medicine Approach in the Multi-Modal Management of Chronic Equine Gastric Ulcer Syndrome (EGUS): A Clinical Commentary. Animals : an open access journal from MDPI, 2025.
Ultrasonographic features of gastric mucosal hypertrophy in dogs receiving chronic omeprazole: a retrospective case series. Journal of the American Veterinary Medical Association, 2026.
Case report: Fundic gland polyps caused by long-term omeprazole use in a Maltese dog. Frontiers in veterinary science, 2023.