Petco Text Logo
Petco Pet Logo

  • Two Easy Ways to Start Earning Rewards!

    rewards header
    Become a member today!
    Members-only pricing and offers, personalized care notifications, Vital Care points back on every purchase and more!
    Already a member? Sign in
    Petco Pay LogoBecome a credit card member today!

    Earn 2X Pals Rewards points at Petco
    when you use Petco Pay!

    APPLY NOW
    Learn More About Petco Pay Benefits

Why does my cat have a lip sore? Is it a rodent ulcer or allergy?

Updated On September 23rd, 2025

Pet's info: Cat | Domestic Mediumhair | Male | neutered | 11 years and 7 months old

My cat has what looks like some kind of sore on his upper lip. I am concerned about what it could be. Would you be able to tell from the attached pictures?

This question includes photos that may contain sensitive content. Click to view.

View more to consider that the photos may include sensitive content.

4 Answers

Most Helpful Answer

Image profile

Answered By Lauren Kennedy, DVM

Veterinarian

Published on August 24th, 2017

This appears to be what is commonly referred to as a 'rodent ulcer'. The most common cause for these to pop up in cats is an allergy, typically to something in the food. Sometimes these will resolve in their own, however sometimes they can become infected, long lasting, and problematic. If they become very large and painful it can discourage the cat from wanting to eat. If this ulcer has been present for more than 2 weeks it is probably not going to go away on its own. At that time I would recommend taking you cat to the vet for treatment. Nathaniel may need antibiotics and an immunsuppresive drug like steroids or Atopica. If the lesions keep coming back he may need to be on an immunosuppressive long term and/or a hypoallergenic diet. I hope this helps. Thanks for using Petco Pet Education Center, formerly Petcoach. Best of luck.

Vote icon

3Pet Parents found this answer helpful

Other Answers

  • Image profile

    Answered By David Elbeze, DVM, MRCVS

    Veterinarian

    Published on October 1st, 2018

    It looks like a condition also known as "rodent ulcer", it's an autoimmune condition that is also linked to allergies, you will need to take him to the vet in order to get treated for that with steroids.

    Vote icon

    1Pet Parents found this answer helpful

  • Image profile

    Answered By David Elbeze, DVM, MRCVS

    Veterinarian

    Published on June 14th, 2018

    IT looks like a condition also known as "Rodent Ulcer", it's an autoimmune condition, at the moment it looks very mild and it is probably not causing your cat any discomfort but it might get worse in the future and might require treatment if it does.

    Vote icon

    1Pet Parents found this answer helpful

  • Image profile

    Answered By Jeffrey Milner

    Veterinarian

    Published on August 2nd, 2017

    That looks like something called a rodent ulcer to me. These generally require treatment with antibiotics and steroids to get rid of the problem. You should seek out some veterinary care to obtain these drugs. Hope this helps.

    Vote icon

    2Pet Parents found this answer helpful

See More Answers

Related Questions

Petco Pet Education Center
Health & Wellbeing
What to do if my cat has a small hole with pus coming from its ear?
Is your cat's ear hole oozing pus? A Petco vet explains potential infections like abscesses from bites, advising immediate vet care, antibiotics, and recovery.
Updated on September 23, 2025
Petco Pet Education Center
Health & Wellbeing
My pet has worsening sores and scratches. Could it be an infection?
Nike's worsening sores and constant scratching worry his owner. A certified Petco veterinarian offers expert guidance on potential causes like bacterial infections and next steps.
Updated on December 04, 2025
Petco Pet Education Center
Food & Nutrition
My cat is chunky. What food and steps can I take to help him lose weight?
Is your cat overweight? A certified vet offers guidance to help your tubby tabby lose weight. Get essential diet and food recommendations to slim down your cat!
Updated on September 23, 2025
Petco Pet Education Center
Health & Wellbeing
Cat sick and still has fleas after vinegar treatment. What now?
Cat still scratching and not eating after vinegar flea treatment? A certified vet reveals why it fails and offers effective solutions for your cat and home.
Updated on September 23, 2025
Petco Pet Education Center
Health & Wellbeing
My kitten had ringworm. Vet says in blood, untreatable, no meds?
Confused about your 6-month-old kitten's ringworm diagnosis, oral meds, or vaccinations? A trusted vet offers a second opinion on your pet's health concerns.
Updated on September 23, 2025
Petco Pet Education Center
Health & Wellbeing
My cat has a weepy wound she keeps licking. Does it need stitches?
Is your cat's weepy wound concerning you? A certified vet offers guidance on home care, when to disinfect, and signs to watch for before seeking professional help.
Updated on September 23, 2025
image
Have A Vet Question?

Book an appointment with the pros – our expert vets are here to help.

Book Now

Sponsored