What are the common causes of mouth ulcers in dogs and cats?

Mouth ulcers can result from dental disease, local inflammation, oral infection, or underlying systemic illness. The specific cause requires a vet examination along with blood work, imaging, or tissue sampling to confirm — a veterinary assessment is recommended.

What can I do at home to ease my pet's mouth discomfort?

You can switch to soft or pureed food, monitor appetite and any bleeding, and take photos or video of the mouth to share with your vet. If there is severe bleeding or your pet cannot eat, seek veterinary care immediately.

What tests will the vet run to find the cause?

Common diagnostics include a complete blood count, biochemistry panel, urinalysis, dental X-rays, and cytology smears. A biopsy may be performed when needed to confirm the diagnosis and guide the treatment plan.

Can mouth ulcers come back?

Some cases may recur, particularly when chronic periodontal disease or an underlying condition is involved. Identifying and addressing the root cause, along with regular oral health checks and home care guidance, can reduce the risk of recurrence — discuss a monitoring plan with your vet.

How much do the tests and treatment usually cost?

Costs vary by clinic and region — ask your vet for an estimate before proceeding.

Disease Guide

Oral Stomatitis & Mouth Ulcers in Dogs and Cats: Symptoms, Diagnosis & Care [2025]

Inflammation and ulceration of the oral mucosa — especially common in cats

Take 1 minute to check the symptoms first

Last updated: 2026/01/06

Pethealthmap Editorial Team

Sources: WSAVA, AVMA, National Taiwan University Veterinary Hospital

When to See a Vet

Seek immediate veterinary care (emergency)

•Unable to eat or drink for more than one day and appears depressed
•Persistent heavy bleeding from the mouth that is difficult to stop on its own
•Accompanied by difficulty breathing or obvious trouble swallowing

Schedule a veterinary visit as soon as possible (within 24-72 hours)

•Clearly reduced eating or intermittent refusal to eat
•Persistent drooling or frequent lip licking that affects daily activities
•Redness, swelling, ulcers, or abnormal patches in the mouth

01What symptoms indicate something is wrong?

Oral stomatitis and ulcers are often painful; changes in eating habits and overall energy level are the most common signs.

Pain when eating, difficulty chewing, or intermittent refusal to eat
Increased drooling, especially noticeable during meals or when licking
Visible redness, swelling, ulcers, or white or blood-tinged patches in the mouth
Noticeable bad breath or oral bleeding, possibly accompanied by weight loss
Decreased activity, lethargy, and persistent loss of appetite

02How can you assess the situation at home? Key things to watch for and when to go to the emergency clinic

Observing and recording details at home helps the vet quickly understand the progression and severity of the condition.

Note when symptoms first appeared and whether they are worsening daily or coming and going
Measure and record daily food intake and any food preference changes (e.g. switching from dry to wet food)
Observe whether energy levels or activity have dropped, or if your pet seems unusually sleepy
Take photos of the mouth or short videos of eating to share with your vet at the appointment
Monitor urination and defecation for normality to help rule out systemic disease
If there is ongoing bleeding, note how often and how much, and seek veterinary care promptly

03How will the vet diagnose the problem? Common diagnostic tests

The vet will combine blood work, imaging, and cytology or biopsy to determine the underlying cause and guide treatment.

Complete blood count (CBC)

assess for infection or anaemia

Biochemistry panel

evaluate liver, kidney, and metabolic function

Urinalysis

help identify whether a systemic disease is contributing

Dental X-rays

examine tooth roots and surrounding bone for changes

Cytology (impression smear)

preliminary differentiation between inflammation and neoplasia

Biopsy if needed to confirm a pathological diagnosis

04What treatment and aftercare is needed? Medications, diet changes, and home care guide

Treatment typically includes pain management and inflammation control; diet adjustments and scheduled follow-ups are also part of the care plan.

Pain relief and anti-inflammatory medications to manage oral pain and swelling
Short-term hospitalisation when necessary to monitor food intake and pain levels
Switch to soft, wet, or pureed food to reduce discomfort during eating
Regular recheck visits to assess healing and perform debridement or dressing changes as needed
Ongoing monitoring of weight and appetite — report any concerning changes to your vet promptly
Follow-up at a clinic experienced in veterinary dentistry or oral medicine is recommended

05What should you prepare before seeing the vet? Key information to help the vet identify the cause quickly

Write down when symptoms started and how they have changed day by day

Record food and water intake over the past three days to share with the vet

Bring a list of any current medications or supplements to avoid missing anything

Take clear photos or short videos of the affected area in the mouth before the visit

Bring any previous test results or imaging files if available

Consider calling ahead to book a clinic that offers dental examination and oral care

This content is for reference only and cannot replace a professional veterinary diagnosis. If your pet shows signs of illness, please seek veterinary care promptly.