# Ulcerative Stomatitis in Dogs: Mouth Ulcers Explained Ulcerative stomatitis in dogs is inflammation of the mouth lining that breaks down into open, painful sores. These ulcers can come from immune disease, severe dental infection, kidney failure, burns, or contact with caustic substances. Because mouth pain often shows up as subtle changes at home, owners frequently miss the early signs. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - Ulcers in a dog's mouth are a sign, not a diagnosis. A veterinarian needs to find the underlying cause before treatment can work. - Kidney failure is a major cause. When kidneys fail, waste products build up and irritate the mouth lining, a pattern called uremic stomatitis in dogs. - Common owner-visible signs include drooling, dropping food, bad breath, pawing at the mouth, and refusing to eat hard kibble. - Diagnosis usually requires an exam under sedation or anesthesia, plus blood work, dental X-rays, and sometimes a biopsy. - Treatment depends on the cause and may include dental cleaning or extractions, immune-suppressing drugs, kidney support, pain control, and a softened diet. ## What Is Ulcerative Stomatitis in Dogs? Stomatitis means inflammation of the mucosal lining anywhere in the mouth [1]. The word "ulcerative" describes what that inflammation looks like: the surface tissue breaks down and leaves raw, open sores. In dogs, this inflammation can affect the gums, the inside of the lips and cheeks, the tissue under the tongue, and the back of the throat [1]. It can extend beyond simple gingivitis and periodontitis into deeper tissue [1]. When it reaches the back of the mouth, it may even make it hard for a veterinarian to pass a breathing tube during anesthesia [1]. One specific pattern veterinarians recognize is canine chronic ulcerative stomatitis, or CCUS. It is a painful, often debilitating condition of the oral cavity that is suspected to have an immune-mediated component [2]. In plain terms, the dog's own immune system appears to be attacking the mouth lining. A related pattern is lymphoplasmacytic stomatitis, which simply describes the type of inflammatory cells found on biopsy. This finding is common and nonspecific, meaning it does not by itself tell your veterinarian what is driving the problem [3]. ## Signs Owners Notice at Home Mouth pain in dogs is easy to underestimate. Dogs keep eating long after a person would have stopped. Watch for changes in how your dog eats, not just whether your dog eats. Common signs include: - Drooling, sometimes with blood-tinged saliva - Bad breath that does not improve with brushing - Dropping food, chewing on one side, or swallowing without chewing - Refusing hard kibble but eating soft food - Pawing at the mouth or rubbing the face on furniture - Reluctance to have the muzzle or mouth touched - Weight loss and reduced grooming - Whining while eating or yawning Some of these signs overlap with other problems. Bad breath, for example, can also point to stomach issues, which is covered in [Dog Bad Breath Caused By Stomach](/knowledge/veterinary-medicine/dental-care/dog-bad-breath-caused-by-stomach). If your dog is drooling and refusing food after chewing on something, a swallowed object is another possibility, described in [Dog Ate a Foreign Object: Signs of Obstruction and When to Go to the Vet](/knowledge/veterinary-medicine/emergency-and-first-aid/dog-ate-foreign-object-obstruction). Because the mouth is involved in picking up food, chewing, and swallowing, any disease there can lead to malnutrition and dehydration [4]. That is why early diagnosis matters so much. Oral diseases are most effectively treated when caught early, and many otherwise stay hidden until they are advanced [4]. ## Causes and Risk Factors Ulcers in the mouth have many possible causes. Your veterinarian's job is to sort out which one applies to your dog. ### Immune-Mediated Disease Canine chronic ulcerative stomatitis is suspected to be immune-mediated, meaning the immune system plays a central role [2]. Other immune-related conditions in dogs, such as pemphigus foliaceus, can also cause inflammation that affects body surfaces, and researchers have studied these as a comparison group when looking at inflammatory disease in dogs [5]. Some dogs with immune-driven inflammation develop lesions in more than one location, including around the eyes [6]. ### Uremic Stomatitis in Dogs When the kidneys fail, they can no longer clear waste products from the blood. Those wastes irritate the mouth lining and can produce ulcers. This is called uremic stomatitis in dogs. It is a distinct form of stomatitis, separate from immune-mediated disease, and it is grouped with other causes such as caustic material ingestion, electrical burns, and irritants [1]. If your dog has kidney disease, mouth ulcers are a warning sign that the disease may be advancing. Uremic stomatitis also tends to cause significant bad breath and drooling. ### Dental and Periodontal Disease Contact lesions from periodontal disease are particularly common in dogs with lymphoplasmacytic oral inflammation [3]. In simple terms, severely diseased teeth and the bacteria around them can irritate the nearby mouth lining and keep it inflamed. Some of these dogs also have CCUS, and some do not, which makes diagnosis tricky [3]. ### Trauma, Burns, and Caustics Chewing electrical cords, lapping or biting caustic chemicals, and chewing on sharp objects can all burn or cut the mouth lining and leave ulcers [1]. These cases often have a clear history, such as a missing cord end or an open cleaning product. ### Other Causes Eosinophilic stomatitis and Wegener's granulomatosis are other severe oral inflammatory conditions recognized in dogs [7]. Your veterinarian may consider these when the pattern of lesions or the biopsy results do not fit the more common causes. ## How Veterinarians Diagnose It Diagnosis starts with a full oral examination. A complete oral exam should be part of every physical examination, because problems in the mouth are easy to miss otherwise [4]. Many dogs will not allow a thorough look while awake, so sedation or anesthesia is often needed. Expect some combination of the following: | Test or step | What it looks for | |---|---| | Full oral exam under sedation | Location, size, and pattern of ulcers | | Blood work and urinalysis | Kidney disease, liver disease, infection, anemia | | Dental X-rays | Diseased teeth, bone loss, retained roots | | Biopsy of the ulcer edge | Immune cells, granulomas, cancer | | Culture or swab | Bacterial or fungal infection | | Trial of dental treatment | Whether contact lesions improve after cleaning or extraction | The distinction between contact lesions and CCUS matters. In one review of 42 dogs with lymphoplasmacytic stomatitis treated surgically, patients were first grouped by lesion distribution and X-ray findings, then regrouped based on how they responded to treatment [3]. That study also questioned the common assumption that dogs should be treated like cats with chronic gingivostomatitis, where partial to full-mouth extractions are the mainstay [3]. The takeaway for owners is that dogs are not cats, and full-mouth extraction is not automatically the answer. ## Treatment Options Treatment targets the cause. There is no single drug or procedure that fixes every case. ### Dental Treatment If contact lesions from periodontal disease are the driver, treating the teeth is the first step. That may mean a professional cleaning under anesthesia, or extraction of specific diseased teeth. Your veterinarian will decide how aggressive to be based on X-rays and exam findings. ### Immune-Suppressing Medication For suspected immune-mediated CCUS, veterinarians may prescribe drugs that calm the immune response. A clinical trial evaluated a combination of cyclosporine and metronidazole in 10 dogs with biopsy-confirmed CCUS, giving cyclosporine at 5 mg/kg for one week, then adding metronidazole at 15 to 20 mg/kg, both once daily by mouth, with the cyclosporine interval lengthened over time [2]. Dogs were followed for 6 months and scored with a 32-point disease activity index, and regular drug monitoring was performed [2]. This is a specific protocol from one study, not a universal recipe. Your veterinarian calculates the dose and schedule from your dog's weight, lab work, and response. Cyclosporine is also used in other inflammatory conditions in dogs, including some eye and skin diseases, at doses set by the treating veterinarian [6]. ### Kidney Support If uremic stomatitis is the cause, the focus shifts to managing kidney disease. That typically means fluids, a kidney-friendly diet, phosphate control, and medications to reduce nausea and stomach acid. Mouth ulcers often improve when the underlying kidney problem is better controlled. Your veterinarian will set the specific plan. ### Pain Control and Supportive Care Pain management is a core part of treatment, not an extra. Anti-inflammatories, other pain medications, and sometimes topical rinses or gels can help. Never give human pain relievers to a dog without veterinary direction, because several common ones are toxic to dogs. Soft food, warmed food, and hand feeding can keep a painful dog eating. Some dogs need a feeding tube for a period while the mouth heals. ### Other Conditions Eosinophilic stomatitis and Wegener's granulomatosis may need different drug combinations, and the approach is less well established in veterinary research [7]. Your veterinarian may refer you to a veterinary dentist or an internal medicine specialist. ## Recovery, Outlook, and Long-Term Management Outlook depends heavily on the cause. Dogs with contact lesions from dental disease often improve after the teeth are treated. Dogs with immune-mediated CCUS may need months of medication and monitoring, and some need lifelong management. Response to drug treatment for CCUS is generally poor with older approaches, which is why newer combinations are being studied [2]. Dogs with uremic stomatitis have a guarded outlook because the underlying kidney disease is progressive. The mouth ulcers can be managed, but the kidney disease itself cannot be cured. Long-term care usually includes: - Regular rechecks with blood work, especially if your dog takes immune-suppressing drugs - Therapeutic drug monitoring when cyclosporine is used [2] - Home dental care if your dog will tolerate it, started only after the mouth has healed - Soft or moistened food during flare-ups - Weight checks at home or at the clinic Keep in mind that mouth disease can hide for a long time. A complete oral exam at every physical exam is the best way to catch problems early [4]. ## Prevention You cannot prevent every cause of mouth ulcers, but you can lower some risks. - Keep electrical cords secured and out of reach. - Store cleaning products, batteries, and caustic chemicals where your dog cannot reach them. - Brush your dog's teeth or use veterinary-approved dental products, and schedule professional cleanings as recommended. - Keep up with wellness visits so kidney disease and dental disease are caught early. - Treat underlying conditions such as atopic dermatitis, which involves chronic inflammation, with your veterinarian's guidance [5]. - Watch for mouth pain signs and act on them quickly instead of waiting. ## Limitations and When to Contact a Veterinarian No article can tell you what is causing your dog's mouth ulcers. Individual cases need a veterinarian who can examine your dog, run tests, and set treatment. Contact your veterinarian the same day if you notice: - Drooling that started suddenly - Refusing all food for more than 24 hours - Bad breath with blood in the saliva - Visible sores, swelling, or bleeding in the mouth - Pawing at the mouth or crying while eating Go to an emergency clinic now if: - Your dog cannot swallow or is choking - There is heavy bleeding from the mouth - You suspect your dog chewed an electrical cord or ate a caustic substance - Your dog is weak, collapsing, or breathing with effort - Your dog has not urinated or is vomiting repeatedly with known kidney disease Call a routine visit if: - Your dog has gradually worsening bad breath - Your dog is dropping food or chewing on one side - Your dog has lost weight without a clear reason - You see a small sore that has not healed in a week ## Frequently Asked Questions ### What does ulcerative stomatitis look like in a dog's mouth? It looks like red, raw, open sores on the gums, lips, cheeks, tongue, or back of the throat. The tissue around the sores is often swollen and inflamed. Many dogs also have heavy drooling and foul breath. ### Is uremic stomatitis in dogs the same as kidney failure? It is a complication of kidney failure, not a separate disease. When the kidneys cannot clear waste products, those wastes irritate the mouth lining and cause ulcers. If your dog has kidney disease and develops mouth sores, tell your veterinarian right away. ### Can mouth ulcers in dogs heal on their own? Minor ulcers from a small cut or burn can heal with time and supportive care. Ulcers from immune disease, kidney failure, or severe dental infection will not resolve without treatment. Any sore that lasts more than a few days needs a veterinary exam. ### Do dogs with stomatitis need all their teeth removed? Not usually. That approach is standard for cats with chronic gingivostomatitis, but dogs are different. A review of surgically treated dogs found that only a minority likely need full-mouth extractions, and treatment should be based on each dog's lesion pattern and response. ### What can I feed a dog with a painful mouth? Soft, moist food at room temperature or slightly warmed is usually easiest to eat. You can soften kibble with warm water or offer canned food. Ask your veterinarian about pain medication before meals, because controlling pain often helps a dog eat more comfortably. ### How long does treatment take? It varies widely. Dental-related cases may improve within days to weeks after treatment. Immune-mediated cases often need months of medication and monitoring, and some dogs need lifelong care. Your veterinarian will set a recheck schedule based on your dog's response. ## 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) - [Pancreatitis In Dogs](/knowledge/veterinary-medicine/clinical-methods/pancreatitis-in-dogs) - [Dog Bad Breath Caused By Stomach](/knowledge/veterinary-medicine/dental-care/dog-bad-breath-caused-by-stomach) - [Dog Ate a Foreign Object: Signs of Obstruction and When to Go to the Vet](/knowledge/veterinary-medicine/emergency-and-first-aid/dog-ate-foreign-object-obstruction) - [Mange In Dogs](/knowledge/veterinary-medicine/clinical-methods/mange-in-dogs) - [Stomatitis in Dogs: Mouth Symptoms and Causes](/knowledge/veterinary-medicine/dental-care/stomatitis-dogs-symptoms-causes) - [Eosinophilic Stomatitis in Dogs: Mouth Sores and Treatment](/knowledge/veterinary-medicine/dental-care/eosinophilic-stomatitis-dogs) - [Chronic Stomatitis in Dogs: Causes and Treatment](/knowledge/veterinary-medicine/dental-care/chronic-stomatitis-in-dogs) ## References 1. [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. 2. [Medical Management of Canine Chronic Ulcerative Stomatitis Using Cyclosporine and Metronidazole](https://pubmed.ncbi.nlm.nih.gov/36650996/). Journal of veterinary dentistry, 2023. 3. [Surgical outcomes in canine lymphoplasmacytic stomatitis: a retrospective study of 42 dogs (2012-2022)](https://pubmed.ncbi.nlm.nih.gov/41445593/). Frontiers in veterinary science, 2025. 4. [Disorders of the Mouth in Dogs - Dog Owners](https://www.merckvetmanual.com/dog-owners/digestive-disorders-of-dogs/disorders-of-the-mouth-in-dogs). Merck Veterinary Manual. 5. [Systemic Inflammation in Dogs With Atopic Dermatitis Compared to Healthy Dogs and Dogs With Pemphigus Foliaceus: A Study Using a Limited Cytokine Panel](https://pubmed.ncbi.nlm.nih.gov/42692466/). Veterinary dermatology, 2026. 6. [Idiopathic Granulomatous Inflammation of the Periocular Structures in Four Dogs: Clinical, Histopathological, and Imaging Findings and Therapeutic Outcome](https://pubmed.ncbi.nlm.nih.gov/42799346/). Veterinary ophthalmology, 2026. 7. [Management of Severe Oral Inflammatory Conditions in Dogs and Cats](https://pubmed.ncbi.nlm.nih.gov/34838249/). The Veterinary clinics of North America. Small animal practice, 2022. ## Further Reading - [Merck Veterinary Manual: Dog Owners](https://www.merckvetmanual.com/dog-owners) - [Cornell Richard P. Riney Canine Health Center: Canine Health Information](https://www.vet.cornell.edu/departments-centers-and-institutes/riney-canine-health-center/canine-health-information) - [American Veterinary Medical Association: Pet Care](https://www.avma.org/resources-tools/pet-owners/petcare)