Rodent Ulcers in Cats. How Serious Are They?

What is a Rodent Ulcer in Cats?

A rodent ulcer, also known as an indolent or eosinophilic ulcer, is a type of sore or lesion that can develop on a cat’s lips, face, or skin (Bajwa, 2019). These ulcers are typically found on or around a cat’s mouth, specifically on the upper lips near the whisker pads. Despite the name, rodent ulcers have no connection to rodents – the term likely originated from the ulcer’s nibbled or “gnawed” appearance.

While rodent ulcers may look concerning, they are usually not a serious issue in cats. The lesions tend to be benign, self-limiting, and non-painful (The Spruce Pets, 2023). Rodent ulcers are actually considered a reaction pattern triggered by the cat’s immune system, rather than an infection or disease process.

Citation: Bajwa, J. (2019). Feline indolent ulcers and their significance. PeerJ, 7, e669.

Citation: The Spruce Pets. (2023, March 31). Rodent ulcers in cats.

Causes and Risk Factors

The exact cause of rodent ulcers in cats is not fully understood, but research suggests it may be related to the feline eosinophilic granuloma complex, an immune-mediated disease [1]. Potential causes and risk factors include:

– Allergies – cats may develop rodent ulcers in response to allergies to things like flea bites, food, pollen, or household products. Flea allergic dermatitis is a common cause [2].

– Stress – stress is believed to play a role in triggering the abnormal immune response that leads to rodent ulcers.

– Genetics – purebred cats like Persians and Himalayans seem to be at higher risk for developing rodent ulcers [3].

– Middle-aged and older cats are more prone to rodent ulcers.

– Male cats get rodent ulcers more often than females.

– Trauma to the lips – previous injuries may predispose cats to ulcer development.


Rodent ulcers in cats often first appear as red, raised lesions on the lips, particularly on the upper lips. The lesions can range in size from small bumps to large, disfiguring ulcers. As the name suggests, the ulcers have a “gnawed” appearance, like the skin has been nibbled on by a rodent.

Visible symptoms of rodent ulcers include:1

  • Red, raised lesions on the lips
  • Crusting around the lesions
  • Bleeding or oozing from the ulcers
  • Loss of tissue and skin disfigurement in severe cases

In terms of behavioral changes, cats with rodent ulcers may:2

  • Paw at their mouth due to irritation and pain
  • Have difficulty eating or drink less water due to mouth pain
  • Become reclusive due to disfigurement of their face


A veterinarian will diagnose a rodent ulcer through a physical examination of the cat and inspection of the lesion. The vet will look for key characteristics of a rodent ulcer, including a raised border and loss of pigment in the center of the lesion [1].

To confirm the diagnosis, the vet may perform a biopsy by taking a small sample of the affected tissue and examining it under a microscope [2]. A biopsy can help rule out other possible causes such as cancer.


Treatment aims to control inflammation and reduce the size of lesions. Several options exist:


Surgical removal of the lesions may be an option, but recurrence is common. Surgery carries risks of infection and scarring (Source).


Radiation therapy can reduce inflammation and lesion size. It may lead to longer remission periods compared to other therapies. Radiation therapy requires anesthesia and multiple visits over weeks (Source).

Other Options

Other therapies like cryosurgery, laser therapy, and topical medications may provide symptom relief. Response varies between individual cats. Allergy testing and immunotherapy could reduce flare-ups if allergies are the underlying trigger (Source).

Home Care and Prevention

There are some things you can do at home to care for a rodent ulcer wound and help prevent future occurrences:

Wound Care:

  • Keep the wound clean by gently cleaning with saline solution. Avoid harsh cleaners.
  • Apply an antibiotic ointment prescribed by your vet to prevent infection.
  • Use an Elizabethan collar to prevent your cat from licking or scratching the wound.
  • Check the wound daily for signs of infection like discharge or foul odor. Contact your vet if you notice anything abnormal.


  • Treat any underlying allergies. Your vet may prescribe antihistamines or immunotherapy.
  • Use flea control products to prevent flea allergy dermatitis.
  • Avoid plastic or ceramic food bowls which can cause chin acne leading to ulcers. Use metal or glass bowls instead.
  • Manage stress which may worsen symptoms. Increase playtime and give your cat safe spaces to retreat to.
  • Discuss nutritional supplements with your vet that may help strengthen skin.

While home care can help manage a rodent ulcer, it’s important to follow up with your vet and not try to treat it solely on your own at home.


The prognosis for rodent ulcers in cats depends on whether the underlying cause is identified and treated successfully. According to the Spruce Pets, if the underlying cause like allergy, infection, or other disease is addressed, the prognosis for complete resolution of rodent ulcers is good.1

However, if the underlying cause remains unidentified and untreated, rodent ulcers tend to recur and can be challenging to manage long-term. The lesions may resolve temporarily with symptomatic treatment like steroids, but tend to return when treatment is stopped according to VCA Hospitals.2

Identifying and managing comorbidities like food allergies, flea allergy dermatitis, atopy, or dental disease optimizes the prognosis. Rodent ulcers have a good prognosis if the underlying disease process can be controlled, reducing recurrence risk.

Living with a Rodent Ulcer

Rodent ulcers can impact a cat’s quality of life, but the condition is manageable with proper treatment and care. According to the Spruce Pets, while rodent ulcers look unpleasant, they usually don’t cause the cat much discomfort[1]. However, in some cases, larger or infected ulcers can be painful. Rodent ulcers may make it difficult for the cat to eat comfortably if the ulcers are on or near the lips and mouth.

Cats with rodent ulcers need to be monitored for signs that the ulcers are getting worse or becoming infected, which would require veterinary treatment. The VCA Hospitals recommends checking for ulcer growth, discharge, bleeding, loss of appetite, or other signs of pain[2]. Owners should follow up with the vet as directed and not try to self-treat worsening ulcers at home.

To help manage rodent ulcers at home, owners can apply antibiotic ointment prescribed by the vet and keep the area clean. Soft foods may make eating more comfortable. While rodent ulcers cannot be cured, they often go away on their own eventually. With proper care and monitoring, cats can continue to live a good quality of life.


When to See a Vet

If your cat has a small rodent ulcer that does not seem to be bothering them, it may be okay to monitor it at home initially. However, there are certain warning signs that indicate a vet visit is needed:

Signs the ulcer is getting worse or not healing such as increasing size, oozing, or bleeding. Persistence beyond 2-3 weeks without improvement.

Difficulty eating or signs of pain around the mouth like drooling or pawing at the face. Not wanting to eat hard food or treats. Weight loss. (VCA Hospitals)

The ulcer has an irregular border, is rapidly growing, or looks infected. The cat stops grooming or seems lethargic. You see swelling of the lips, face, or lymph nodes. These may indicate a serious problem requiring prompt veterinary attention.

Emergency symptoms that require immediate evaluation include a large, bleeding ulcer or one affecting breathing or vision. Trouble breathing, squinting eyes, or extreme swelling, redness, pain or bleeding from the mouth are urgent situations. If the cat is in distress, take them to an emergency vet right away. (The Spruce Pets)


A rodent ulcer is a type of skin cancer that can develop on a cat’s head, face or neck. While rodent ulcers are usually not fatal if treated properly, they can be serious if left untreated and allowed to grow.

The key points to remember about rodent ulcers in cats are:

  • They are caused by sun exposure and damaged skin cells.
  • Symptoms include scabs, ulcers and loss of hair around affected areas.
  • Veterinary exams and biopsies are needed for diagnosis.
  • Treatment options include surgery, radiation therapy, chemotherapy creams.
  • Home care involves keeping the area clean and protecting from sun exposure.
  • With early treatment, prognosis is often good.

For cat owners, it’s important to monitor your cat’s skin closely and watch for any abnormal scabs or sores, especially on the head, face or neck. Schedule regular vet checkups to catch any signs early. Limit sun exposure, keep your cat’s skin protected, and contact your vet promptly about suspicious lesions to give your cat the best chance of recovery from a rodent ulcer.

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