Gastric Ulcers in Dogs and Cats: Signs and Safe Care

The stomach is a genuinely hostile place. It produces acid strong enough to break down bone fragments, and it does this every day for a lifetime without digesting itself. The reason is an intricate protective system — a mucus layer, a bicarbonate barrier, a rich blood supply, and rapid cell turnover — that shields the lining from its own contents.

A gastric ulcer is what happens when that protection fails somewhere. Acid reaches the lining directly, erodes through the surface, and creates a raw, painful defect that can bleed. In dogs and cats this is not a common everyday diagnosis, but it is a serious one, and it is strongly associated with a handful of causes that owners can meaningfully influence.

The most important of those, from an owner's point of view, is medication. Several drugs that are entirely appropriate under veterinary direction become dangerous when doses are doubled up, when courses are extended without monitoring, or when human painkillers are given to a pet in good faith. This guide covers how ulcers develop, the signs that should prompt a call, how veterinarians investigate, and what safe medication practice at home looks like.

Important: This article shares general educational information for pet owners and is not a substitute for an in-person veterinary examination, diagnosis, or treatment. For any medical concern or emergency, contact your veterinarian promptly.

How the Stomach Protects Itself

Understanding the defenses makes the causes of ulceration much easier to follow. The stomach lining is coated in a layer of mucus that physically separates acid from cells. Beneath it, bicarbonate secretion neutralizes acid that penetrates the mucus. A dense network of blood vessels supplies oxygen and nutrients and carries away any acid that gets through. And the surface cells themselves are replaced constantly, so minor damage is repaired before it becomes significant.

Ulceration occurs when one or more of these defenses is compromised, when acid production rises beyond what the defenses can handle, or when both happen at once. Anything that reduces blood flow to the stomach lining is particularly dangerous, because it removes the repair capacity at the same moment as the injury.

This explains why ulcers appear in situations that seem unrelated to the digestive system at all — shock, severe dehydration, heatstroke, prolonged strenuous exertion, and major illness elsewhere in the body all reduce blood flow to the gut, and all are recognized risk situations.

• Mucus layer: the physical barrier between acid and cells.
• Bicarbonate: neutralizes acid that reaches the surface.
• Blood flow: delivers repair capacity and removes acid.
• Cell turnover: continuous replacement of damaged lining.
• Prostaglandins: signaling molecules that maintain several of these defenses at once.

What Causes Ulcers in Dogs and Cats

The list is manageable, and a few causes account for most cases seen in general practice.

• Anti-inflammatory medication: non-steroidal anti-inflammatory drugs reduce prostaglandin production, which is how they relieve pain and inflammation but also how they weaken stomach defenses. Veterinary NSAIDs are prescribed with this in mind; human NSAIDs given to pets are a frequent and serious cause of ulceration.
• Steroid medication: particularly at higher doses, for long periods, or combined with an NSAID — a combination veterinarians avoid deliberately.
• Reduced blood flow states: shock, severe dehydration, heatstroke, or major surgery.
• Liver and kidney disease: both are associated with gastric ulceration through several mechanisms.
• Tumors: some gastric and hormone-secreting tumors cause ulceration directly.
• Foreign material: swallowed objects that abrade the lining.
• Toxins and caustic substances: including certain household chemicals and plants.
• Severe systemic illness: sepsis, pancreatitis, and other critical conditions.
• Extreme exertion: recognized in working and racing dogs undergoing prolonged intense activity.
• Inflammatory disease: chronic inflammation of the stomach lining in some patients.

The pattern owners should take from this list is that ulcers rarely appear in an otherwise healthy, unmedicated pet out of nowhere. There is usually a medication, an illness, or an event behind it — which is also why finding the cause is part of the treatment rather than an academic exercise.

Signs That Should Prompt a Call

Early ulceration can be silent or produce only vague signs. The findings below range from subtle to urgent, and several of them are easy to misread as ordinary stomach upset.

• Vomiting: repeated, sometimes containing material that looks like coffee grounds — digested blood.
• Fresh blood in vomit: bright red streaks or clots.
• Black, tarry stool: dark, sticky, foul-smelling feces indicating digested blood from higher in the tract.
• Reduced appetite: or eating and then turning away from the bowl.
• Nausea signs: lip licking, drooling, repeated swallowing, standing hunched over the water bowl.
• Abdominal discomfort: a hunched posture, a praying position with front legs down and rear up, or resenting being lifted.
• Weight loss: over weeks in more chronic cases.
• Pale gums: suggesting blood loss and anemia.
• Weakness or lethargy: disproportionate to any other illness.
• Rapid breathing or collapse: in significant blood loss, which is an emergency.

Black tarry stool deserves particular emphasis because it is so often dismissed. Feces that look almost like tar, with a distinctive sheen and a strong smell, indicate bleeding from the stomach or upper intestine. It is not a normal variation and it warrants a same-day call to your veterinarian.

Cats, as ever, understate. A cat with gastric ulceration may simply eat less, hide more, and lose condition gradually. Any cat with unexplained appetite loss lasting more than a day or two should be examined, and this is one of several reasons why.

Medication Safety at Home

This section is where owners have the greatest direct influence on risk, and it is worth reading carefully even if your pet is currently on nothing at all.

Never give a human pain reliever to a dog or cat unless your veterinarian has specifically directed you to, in a specific dose, for your specific pet. Several common household painkillers cause severe gastric ulceration, kidney injury, or other toxicity in dogs and cats, and cats are particularly sensitive to some of them. A well-intentioned tablet given to a limping dog while waiting for an appointment is one of the more common preventable causes of serious illness in companion animals.

When your veterinarian does prescribe an anti-inflammatory, follow the dose and interval exactly. Do not give extra because your pet still seems sore — call instead. Do not combine a prescribed veterinary NSAID with anything else without checking, including supplements and any medication left over from another pet or another episode.

Give anti-inflammatory medication with food unless directed otherwise, and stop and contact your veterinarian if vomiting, appetite loss, diarrhea, or black stool appear during a course. These are the recognized early warning signs, and stopping promptly on veterinary advice is far better than continuing and hoping.

Where long-term anti-inflammatory treatment is genuinely needed — most commonly for arthritis — your veterinarian will set up a monitoring schedule with periodic examinations and blood tests. Keeping those appointments is not administrative box-ticking; it is how problems are found before they become ulcers.

How Veterinarians Investigate

Vomiting is one of the most common presentations in small animal practice and has dozens of possible causes, so investigation is about narrowing the field efficiently rather than jumping to the stomach.

A thorough history matters enormously here, and it is the one part where the owner supplies most of the information. Your veterinarian will want to know exactly what medications your pet has had — including anything given by another family member — what the vomit and stool have looked like, how long it has been going on, and whether there is any chance of a swallowed object or toxin.

Blood tests are usually the first step. They can reveal anemia from blood loss, changes suggesting liver or kidney disease, and markers of inflammation or other systemic illness. A fecal test for hidden blood may be used, though it needs careful interpretation — meat in the diet can produce a false positive, so your veterinarian may ask you to feed a specific diet for a few days beforehand or to repeat the test. Imaging with radiographs or ultrasound helps rule out foreign bodies, masses, and other abdominal disease.

Endoscopy — passing a camera into the stomach under anesthesia — is the definitive way to see an ulcer, assess its size and depth, and take biopsies. It is not needed in every case, but it is the test that turns a strong suspicion into a confirmed diagnosis, and it can identify an underlying cause such as a tumor or inflammatory disease at the same time.

In practice, many suspected cases in stable patients are managed on the basis of history, examination, blood work, and response to treatment, with endoscopy reserved for severe, recurrent, or unclear cases. Your veterinarian will explain the reasoning for your pet.

What Treatment Involves

Treatment is directed by your veterinarian and generally combines reducing acid, protecting the lining, supporting the patient, and removing the cause.

Acid-reducing medication is the mainstay, and there are several classes with different strengths and durations of action. Your veterinarian chooses based on severity and on what else the pet is receiving. Medications that coat and protect the ulcer surface are sometimes added, and these often need to be given separately from other drugs so they do not interfere with absorption — which is why the timing instructions on the label matter.

Anti-nausea medication improves comfort and helps a patient start eating again, which is itself important for healing. Fluid therapy, either at the clinic or at home, addresses dehydration from vomiting. Pets with significant blood loss may need more intensive support, including transfusion in severe cases.

Removing the cause is often the decisive step: stopping an implicated medication, treating the underlying kidney or liver disease, retrieving a foreign body, or addressing a tumor. Where an ulcer has perforated through the stomach wall, emergency surgery is required — a serious situation that underlines why the earlier warning signs should not be watched and waited on.

Treatment courses are usually measured in weeks rather than days, and stopping early because vomiting has settled is a common route to relapse. Ulcers heal from the surface down, and the outside looks better long before the repair is complete.

Feeding During Recovery

Your veterinarian will give specific dietary instructions, and these should take precedence over general advice. That said, the principles are consistent across most cases.

1. Follow the fasting period, if any, exactly as instructed — and do not withhold food from a cat for longer than directed, as cats are vulnerable to complications from not eating.
2. Reintroduce food in small, frequent meals rather than one or two large ones, which reduces acid surges.
3. Use the diet your veterinarian recommends — often an easily digestible or prescription gastrointestinal formulation — rather than improvising.
4. Avoid fatty foods, table scraps, rich treats, and anything unusual during recovery.
5. Keep fresh water available at all times unless specifically told otherwise.
6. Feed away from other pets so you can see exactly how much your patient is eating.
7. Give medications at the times specified relative to meals, as some work best on an empty stomach and others with food.
8. Return to the normal diet gradually over several days once your veterinarian approves.

Weigh your pet weekly during recovery if you can. Weight is an objective measure that catches a slow decline much earlier than impressions do, and it gives your veterinary team something concrete at the recheck.

Prevention in Practical Terms

Most gastric ulceration in companion animals is either medication-related or illness-related, and both categories offer real opportunities for prevention.

On the medication side: use only veterinary-prescribed pain relief, at the prescribed dose, for the prescribed duration; never combine anti-inflammatory medications; give with food unless told otherwise; attend monitoring appointments for long-term treatment; and stop and call at the first sign of digestive upset during a course.

On the illness side: address dehydration promptly rather than waiting to see whether it improves, take heatstroke prevention seriously in warm weather, and manage chronic kidney and liver disease actively with your veterinarian rather than reactively.

Household safety matters too. Keep all medication — human and veterinary — where a determined dog cannot reach it, and store it in its original container so that if the worst happens your veterinarian knows exactly what was involved. Chewed blister packs and empty bottles are one of the more common emergency presentations in general practice.

For pets on long-term anti-inflammatory treatment for arthritis, discuss the whole picture with your veterinarian rather than the medication alone. Weight management, controlled exercise, joint-friendly home adaptations, and physical therapy can all form part of a plan that supports comfort and mobility, and your veterinarian can advise which combination suits your pet. Supplements marketed for joint or digestive support are not treatments for ulceration and should never be added during an active episode without veterinary approval.

Myths and Facts

Myths, Corrected

• Myth: a dog vomiting occasionally is normal. Occasional vomiting warrants attention; repeated vomiting always does.
• Myth: milk soothes a pet's stomach. It does not, and many adult dogs and cats digest it poorly.
• Myth: human antacids are a safe stopgap. Doses, formulations, and interactions differ; use only what your veterinarian directs.
• Myth: black stool just means they ate something dark. Tarry black stool is a recognized sign of digested blood and needs same-day assessment.
• Myth: if the vomiting stops, the ulcer has healed. Healing takes weeks longer than symptom resolution.
• Fact: NSAIDs are a leading identified cause. Which is why they are prescription-only and monitored.
• Fact: cats hide this well. Reduced appetite may be the only sign.
• Fact: pale gums plus weakness is an emergency. It suggests significant blood loss.

When to Contact Your Veterinarian

Thresholds for Calling

This condition sits in a category where the difference between a routine appointment and an emergency is a matter of a few specific signs.

• Call the same day for: repeated vomiting, vomit resembling coffee grounds, black tarry stool, or appetite loss in a cat.
• Seek emergency care for: fresh blood in vomit, pale or white gums, weakness, collapse, severe abdominal pain, or a distended painful abdomen.
• Stop medication and call if: vomiting, diarrhea, appetite loss, or lethargy begin during any course of anti-inflammatory treatment.
• Call immediately if: your pet has swallowed any human medication, in any quantity.

For any medical emergency, contact your veterinarian or your nearest emergency veterinary hospital immediately rather than waiting for regular opening hours. If a medication has been swallowed, bring the packaging with you.

The Practical Takeaway

What to Remember

Gastric ulcers in dogs and cats are uncommon enough that most owners will never meet one, and serious enough that it is worth knowing the signs anyway. The findings that matter most are the ones easiest to dismiss: a stool that looks unusually black, a vomit that looks like coffee grounds, a cat who has gone quiet and off her food.

The prevention message is narrower and more actionable than for most conditions. Do not give human painkillers to pets. Follow veterinary prescriptions exactly. Attend the monitoring appointments for long-term medication. Store the medicine cabinet where a curious dog cannot reach it. Those four habits address the large majority of avoidable cases.

And if something does go wrong, act on the day rather than the week. Ulcers that are caught while they are still bleeding slowly are treated medically and heal well. Ulcers that are left until they perforate become emergency surgery. The gap between those two outcomes is usually measured in how quickly someone picked up the phone.