Stomach Ulcers in Dogs: Causes, Signs and Care

By Tailwisp Editorial TeamUpdated October 17, 20263 min read

Ulcers can develop quietly and then cause sudden bleeding. Recognizing early signs matters.

What they are

The stomach has a protective lining against acid. When that lining is damaged, acid can erode the tissue and form an ulcer, which can bleed or, in rare cases, perforate.

Common causes

• NSAIDs, both prescribed and human products. See why human painkillers are dangerous for dogs
• Steroids, especially combined with NSAIDs
• Kidney or liver disease
• Severe illness, trauma or shock
• Tumors, such as mast cell tumors. See mast cell tumors in dogs
• Foreign objects or irritating substances
• Extreme exercise or stress in some working dogs

Signs

• Vomiting, sometimes with blood or coffee-ground material
• Black, tarry stool
• Poor appetite and weight loss
• Abdominal pain or a hunched posture
• Pale gums and weakness if bleeding is significant

See dog vomit color guide and dog poop color guide.

When to seek help

Call a vet urgently if you see black stool, vomiting blood, collapse or pale gums. Mention any medications your dog has had, including products bought without a prescription.

Diagnosis

Vets may recommend bloodwork, imaging, endoscopy and tests for the underlying cause. Endoscopy lets them see the ulcer and take biopsies.

Treatment

• Stopping the trigger, such as an NSAID, under veterinary guidance
• Acid-reducing and stomach-protecting medication
• Fluids and anti-nausea medication
• Transfusion or surgery in severe cases
• Diet changes to ease digestion

Follow the plan closely and finish the course even if your dog seems better.

Prevention

• Give medications exactly as prescribed
• Never combine NSAIDs and steroids without your vet's plan
• Do not give human painkillers
• Report vomiting or appetite changes while on medication
• Keep regular checkups for chronic conditions

Common mistakes

• Giving ibuprofen or aspirin without advice
• Ignoring black stool
• Stopping stomach medication early
• Assuming it is just an upset stomach

Troubleshooting

• My dog is on arthritis medication and stopped eating: call your vet right away.
• Stool turned dark: check the diet, but call if tar-like.
• Vomiting returns after treatment: book a recheck.

A simple plan

1. Know your dog's medications.
2. Watch for early signs.
3. Call your vet promptly.
4. Follow treatment.

Real-life examples

A lab given aspirin by an owner develops black stool, and hospital care clears the ulcer. A senior dog with kidney disease has appetite loss that improves with stomach protection. A terrier needs surgery for a perforated ulcer. Early care protects dogs.

Medications and safety

Ask your vet about side effects for any drug you give and what to do if signs appear.

Questions for your vet

If your dog needs an anti-inflammatory for arthritis or injury, ask which drug is safest for him, whether stomach protection is advisable, how long to use it, what side effects to watch for and which signs mean you should stop and call. Write the answers down so everyone who gives medication follows the plan.

Stress, exercise and special cases

Working and sled dogs can develop stomach lesions during prolonged intense exercise, and severely ill dogs may develop stress-related ulcers in hospital, which is why vets often give protective medication in some cases. Feed regular small meals, avoid heavy exertion on an empty stomach and ask about prevention if your dog has a demanding job.

Follow-up after healing

Some dogs need repeat endoscopy or bloodwork to confirm healing, especially if a tumor or chronic disease is suspected. Keep recheck appointments even when your dog looks normal again, since ulcers can heal and recur if the cause remains.

The takeaway

Ulcers often follow medications or illness. Black stool or vomiting blood needs prompt veterinary care.

This article is general educational information, not veterinary advice. Every dog is different. If your dog is unwell, or you are unsure about a symptom, diet change or medication, contact your veterinarian.