# Dog Mouth and Stomach Ulcers: Causes and Treatment Dog ulcers are open sores that can form in the mouth or in the stomach and upper intestine. How to treat dog ulcers depends entirely on where the ulcer is and what caused it, so a veterinary diagnosis comes first. Mouth ulcers are often linked to dental disease or contact irritation, while stomach ulcers usually trace back to medications, illness, or stress on the gut lining. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - Mouth ulcers and stomach ulcers are different problems with different causes and treatments, so the location matters. - Never give human ulcer medications, pain relievers, or antacids to your dog without veterinary guidance. - Stop giving any NSAID or steroid and call your vet if you see vomiting, black stool, or mouth sores. - A vet confirms stomach ulcers with endoscopy, which is considered the gold standard for diagnosis [1]. - Treatment usually involves stopping the cause, acid-suppressing medication, and a bland or prescription diet. ## What Are Dog Mouth and Stomach Ulcers? An ulcer is a break in the surface layer of tissue that exposes the raw layer underneath. In dogs, ulcers show up in two main places. Mouth ulcers are sores on the gums, lips, tongue, inner cheeks, or roof of the mouth. They can be shallow or deep and often come with redness, swelling, and pain when your dog eats or drinks. Stomach ulcers (gastric ulcers) are sores in the lining of the stomach or the first part of the small intestine, called the duodenum. The stomach and duodenum are the primary sites of ulceration in dogs and cats [1]. The stomach lining normally defends itself against strong acid, but when that barrier breaks down, acid can injure the tissue beneath it [1]. These two conditions are not the same. A dog with a mouth ulcer may have a completely healthy stomach, and a dog with a stomach ulcer usually has a normal-looking mouth. Some diseases, though, can cause problems in both areas at once. ## Signs Owners Notice ### Mouth ulcer symptoms - Drooling more than usual - Dropping food or chewing on one side - Bad breath - Red, raw, or bleeding spots in the mouth - Reluctance to eat hard kibble - Pawing at the face or mouth If your dog has persistent bad breath along with mouth sores, see [Dog Bad Breath Caused By Stomach](/knowledge/veterinary-medicine/dental-care/dog-bad-breath-caused-by-stomach) for related information on how gut and dental issues can overlap. ### Stomach ulcer symptoms Stomach ulcer signs in dogs are often vague. Clinical signs are usually nonspecific, and vomiting blood (hematemesis) or black, tarry stool (melena) may or may not appear [1]. Watch for: - Vomiting, sometimes with blood that looks like coffee grounds - Black, tarry stools - Loss of appetite - Weight loss - Painful or tense belly - Weakness or pale gums Black stool is a red flag because it means blood is being digested somewhere in the upper gut. Call your vet right away if you see it. ## Causes and Risk Factors ### Why stomach ulcers happen Several drugs and diseases can disrupt and ulcerate the gastrointestinal mucosal barrier in small animals [1]. The most common culprits include: **NSAIDs and steroids.** Nonsteroidal anti-inflammatory drugs are a leading cause. In one study of 33 dogs with confirmed gastrointestinal ulceration, dogs received a single NSAID, two NSAIDs, a single steroid, or an NSAID plus a steroid [2]. Even dogs given a single COX-2-sparing NSAID at an appropriate dose developed ulcers [2]. All five dogs that received two NSAIDs at the same time had full-thickness perforation [2]. The most common ulcer locations were the duodenum and the pylorus [2]. This does not mean NSAIDs are unsafe when used correctly. It means they carry real risk, especially when combined or used without veterinary supervision. **Other causes.** Severe illness, kidney disease, liver disease, shock, and certain cancers can all reduce blood flow to the gut lining and set the stage for ulcers. Stress from major surgery or critical illness is another factor. ### Why mouth ulcers happen Contact mucositis and contact mucosal ulceration are lesions that form where the mouth lining touches an irritant, allergen, or antigen, often on a tooth surface [3]. In other words, a rough or diseased tooth can rub against the inside of the lip or cheek and create a sore. Other causes include: - Severe periodontal disease - Trauma from chewing on sharp objects - Viral or immune-mediated disease - Kidney disease, which can cause oral sores - Certain medications or toxins If gum disease is part of the picture, see [How To Treat Gum Disease In Dogs](/knowledge/veterinary-medicine/dental-care/how-to-treat-gum-disease-in-dogs). ### A note on home remedies Owners often search for a home remedy for dog mouth ulcer. There is no well-established home treatment that safely resolves a true ulcer. Human oral gels, hydrogen peroxide, salt water rinses, and human pain relievers can irritate the tissue or cause poisoning. Rinsing with plain water and offering soft food may ease discomfort until you see your vet, but these steps do not treat the underlying cause. ## How Veterinarians Diagnose Ulcers ### Mouth ulcers Your vet will examine the mouth carefully, sometimes under light sedation so they can see the back of the throat and under the tongue. Dental radiographs help find diseased teeth or retained roots. Blood work checks for kidney disease, infection, and other systemic causes. ### Stomach ulcers Abdominal ultrasound can show changes consistent with ulceration, but endoscopy is considered the gold standard for diagnosis [1]. Endoscopy means passing a small camera into the stomach while your dog is under anesthesia. It lets the vet see the ulcer directly and take samples if needed. Your vet may also run blood work, a fecal test, and imaging to rule out other causes of vomiting and weight loss. | Feature | Mouth Ulcers | Stomach Ulcers | |---|---|---| | Common signs | Drooling, bad breath, trouble eating | Vomiting, black stool, appetite loss | | Typical causes | Dental disease, contact irritation, kidney disease | NSAIDs, steroids, severe illness, stress | | Best diagnostic test | Oral exam, dental radiographs | Endoscopy (gold standard) [1] | | Main treatment | Treat the cause, dental care, soft diet | Stop trigger, acid suppression, diet change | | Urgency | Usually routine, urgent if bleeding | Often urgent, emergency if bleeding | ## Treatment Options ### How to treat dog ulcers in the stomach Treatment starts with removing the cause. If an NSAID or steroid is involved, your vet will stop it and may switch to a different pain strategy. Never stop a prescribed medication on your own without talking to your vet first. **Acid suppression.** Proton pump inhibitors are the treatment of choice for gastrointestinal ulcers in small animals [1]. These drugs reduce stomach acid so the ulcer can heal. Your veterinarian calculates the dose from your dog's weight and health status. **Other medications.** Depending on the case, your vet may add a mucosal protectant, an anti-nausea drug, or a prokinetic to help the gut move normally. Some dogs need fluids or a blood transfusion if they have lost a lot of blood. **Diet.** Small, frequent meals of a bland or prescription gastrointestinal diet reduce acid exposure and are easier on the stomach. Your vet will tell you how long to keep this up. Acid-suppressant drugs are widely used in dogs, but their effects outside the stomach are still being studied, and veterinary research in this area is limited [4]. That is one reason these medications should be used under veterinary direction, not casually. ### How to treat dog mouth ulcers Treatment depends on the cause. - **Dental disease:** Cleaning, extraction of diseased teeth, and debridement of affected tissue. When full-mouth extractions are done early and radiographs confirm no retained roots, 60 to 80% of affected cats are cured or dramatically improved [3]. This figure comes from cats, but the principle of removing the source of irritation applies to dogs too. - **Contact ulcers:** Removing the offending tooth surface or irritant is the only treatment that provides lasting improvement [3]. - **Kidney disease or systemic illness:** Treating the underlying condition often helps the mouth heal. - **Immune-mediated disease:** Your vet may prescribe medication to calm the immune response. For ulcers on the skin instead of the mouth, see [Dog Skin Ulcers: Causes, Treatment, and When to See a Vet](/knowledge/veterinary-medicine/dermatology/skin-ulcer-dog). ## Recovery, Outlook, and Long-Term Management Most uncomplicated stomach ulcers heal within a few weeks once the trigger is removed and acid suppression begins. Your vet will likely recheck your dog and may repeat imaging or blood work. Mouth ulcers often improve quickly once the source of irritation is gone. If dental extractions were needed, most dogs eat comfortably within days to a couple of weeks. Long-term management may include: - Avoiding the NSAID or steroid that caused the problem, or using it only with a stomach-protecting plan - Regular dental cleanings and home dental care - Monitoring kidney values if kidney disease is the cause - Feeding a diet your vet recommends - Watching for return of vomiting, black stool, or mouth sores For dogs with ongoing digestive signs like gas and loose stool, see [Dog Excessive Gas and Diarrhea: Causes and Relief](/knowledge/veterinary-medicine/digestive-and-urinary-care/dog-excessive-gas-diarrhea). ## Prevention You cannot prevent every ulcer, but you can lower the risk. - Give NSAIDs and steroids only under veterinary supervision, at the dose your vet sets. - Never combine two NSAIDs, and never mix an NSAID with a steroid unless your vet specifically directs it. In one study, all dogs given two NSAIDs at once had full-thickness perforation [2]. - Keep up with dental care to reduce mouth irritation and contact ulcers. - Manage chronic conditions like kidney disease with regular checkups. - Tell your vet about every medication, supplement, and human drug your dog receives. - Seek care early for vomiting, appetite loss, or mouth pain. ## Limitations and When to Contact a Veterinarian This article gives general information. Individual cases need a veterinarian who can examine your dog, run tests, and set a treatment plan. **Call an emergency clinic now if you see:** - Vomiting blood or material that looks like coffee grounds - Black, tarry stool - A swollen, hard, or painful belly - Collapse, weakness, or pale gums - Heavy bleeding from the mouth **Call your vet the same day if you see:** - Your dog stopped eating - Drooling or trouble swallowing that started suddenly - Mouth sores that are spreading or bleeding - Vomiting that will not stop **Schedule a routine visit if you see:** - Bad breath that does not improve with brushing - Mild drooling or chewing on one side - Gradual weight loss - Sores that keep coming back ## Frequently Asked Questions ### Can I treat my dog's ulcer at home? No, you should not try to treat a dog ulcer at home without veterinary guidance. Some supportive steps, like offering soft food and keeping your dog hydrated, may help comfort, but the underlying cause needs a diagnosis. Human ulcer drugs and pain relievers can harm your dog. ### What does a stomach ulcer look like in a dog? Stomach ulcers are internal, so you cannot see them directly. You may notice vomiting, black stool, appetite loss, or belly pain. Some dogs show no obvious signs at all, which is why vague symptoms deserve a vet visit. ### Are certain pain medications more likely to cause ulcers? Yes. NSAIDs and steroids are the main medication-related causes of gastrointestinal ulceration in dogs. Even a single COX-2-sparing NSAID at a proper dose has been linked to ulcers, and combining two NSAIDs sharply raises the risk [2]. Always follow your vet's dosing instructions. ### How long does it take for a dog ulcer to heal? Most stomach ulcers improve within a few weeks once the cause is removed and treatment starts. Mouth ulcers often heal faster, especially after dental treatment. Your vet will set a recheck schedule based on your dog's specific case. ### Can kidney disease cause ulcers in a dog's mouth? Yes. Kidney disease is a known cause of oral ulcers in dogs. When the kidneys cannot filter waste properly, those wastes can build up and irritate the mouth lining. Treating the kidney disease is part of managing the ulcers. ## Related Articles - [Dog Skin Ulcers: Causes, Treatment, and When to See a Vet](/knowledge/veterinary-medicine/dermatology/skin-ulcer-dog) - [Canine Gastric Ulceration: Diagnosis and Management](/knowledge/veterinary-medicine/clinical-methods/canine-gastric-ulceration-diagnosis-management) - [Dog Bad Breath Caused By Stomach](/knowledge/veterinary-medicine/dental-care/dog-bad-breath-caused-by-stomach) - [How To Treat Gum Disease In Dogs](/knowledge/veterinary-medicine/dental-care/how-to-treat-gum-disease-in-dogs) - [Dog Excessive Gas and Diarrhea: Causes and Relief](/knowledge/veterinary-medicine/digestive-and-urinary-care/dog-excessive-gas-diarrhea) - [Why Does My Dog Have Bad Breath And Gas](/knowledge/veterinary-medicine/dental-care/why-does-my-dog-have-bad-breath-and-gas) - [Stomach Ulcers in Dogs: Symptoms, Causes, and Treatment](/knowledge/veterinary-medicine/digestive-and-urinary-care/stomach-ulcers-in-dogs) - [Ulcerative Stomatitis in Dogs: Mouth Ulcers Explained](/knowledge/veterinary-medicine/dental-care/ulcerative-stomatitis-in-dogs) - [Dog Gastritis: Home Care and When to See a Vet](/knowledge/veterinary-medicine/digestive-and-urinary-care/dog-gastritis-home-care) ## References 1. [Gastrointestinal Ulcers in Small Animals - Digestive System](https://www.merckvetmanual.com/digestive-system/diseases-of-the-stomach-in-small-animals/gastrointestinal-ulcers-in-small-animals). Merck Veterinary Manual. 2. [Dogs receiving cyclooxygenase-2-sparing nonsteroidal anti-inflammatory drugs and/or nonphysiologic steroids are at risk of severe gastrointestinal ulceration](https://pubmed.ncbi.nlm.nih.gov/39426398/). Journal of the American Veterinary Medical Association, 2025. 3. [Oral Inflammatory and Ulcerative Disease in Small Animals - Digestive System](https://www.merckvetmanual.com/digestive-system/diseases-of-the-mouth-in-small-animals/oral-inflammatory-and-ulcerative-disease-in-small-animals). Merck Veterinary Manual. 4. [pH-independent effects of acid suppressants in dogs and cats: a One Health perspective and case for further investigation](https://pubmed.ncbi.nlm.nih.gov/39127078/). American journal of veterinary research, 2024. ## Further Reading - [Disorders of the Stomach and Intestines in Dogs - Dog Owners (Merck Veterinary Manual)](https://www.merckvetmanual.com/dog-owners/digestive-disorders-of-dogs/disorders-of-the-stomach-and-intestines-in-dogs) - [American Veterinary Medical Association: First Aid Tips for Pet Owners](https://www.avma.org/resources-tools/pet-owners/emergencycare/first-aid-tips-pet-owners) - [Merck Veterinary Manual: Dog Owners](https://www.merckvetmanual.com/dog-owners)