What Causes Dog Mouth Blisters?

Erin J. Hill

There are a wide variety of potential causes for dog mouth blisters, including kidney disease, cancer, infection, and dental problems. All of these issues should be treated by a licensed veterinarian. Occasionally a dog may get mouth blisters from chewing on hard objects which may splinter and become lodged in the mouth or cut the dog's lip or gums. If this occurs, an infection may take root in the abrasion.

A dog with mouth blisters should be treated by a veterinarian.
A dog with mouth blisters should be treated by a veterinarian.

As part of a normal physical exam, dogs' mouths should be checked since oral health can be a good indicator of overall health. Although in many cases the causes of mouth blisters in dogs are benign and fully treatable, sometimes they are cause for concern. Oral cancer and kidney disease can both lead to mouth blisters. In many cases these will be the only noticeable physical symptom that owners detect.

Kidney disease may cause dog mouth blisters.
Kidney disease may cause dog mouth blisters.

Many times, dog mouth blisters will be caused by underlying dental problems. Gum disease and mouth infections may occur together since bacteria can enter infected gums. Dogs also sometimes chew on things they shouldn't. Pieces of bone, sticks, or other hard items can sometimes lodge in the gums or cheek and bacteria may enter the wound, causing an infection. If a bacterial infection is to blame for the mouth blisters, the area will likely also be inflamed and red.

More serious conditions may also lead to dog mouth blisters. The most serious of these is oral cancer, which often leads to blisters in the back of the mouth close to the throat. Kidney disease may also cause sores or ulcers to appear in the mouth once the condition becomes severe enough.

Owners who notice blisters in their dogs mouths should first try to alleviate any pain. This can be done through oral numbing medications or other painkillers that have been approved by a veterinarian. Dogs should be examined by a vet as soon as possible after the discovery of a mouth ulcer to ensure that it is not serious. Minor infections and sores will typically be treated with medication, while more serious conditions may require ongoing treatment.

Pet owners should not give their dogs any medication without first speaking to a vet. Dog mouth blisters that are accompanied by bleeding, oozing, or severe pain may require immediate medical attention at an emergency vet hospital. This also goes for dogs that have severe fever, vomiting, diarrhea, or loss of appetite. These could be signs of a serious infection or condition.

Numbing cream can be used to temporarily soothe mouth blisters.
Numbing cream can be used to temporarily soothe mouth blisters.

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Discussion Comments


My dog got blisters in her mouth after eating the bones of some animal. I have no idea what it once was, but she thoroughly enjoyed those bones for many months.

I didn't know that a small portion of bone had become lodged in her gums until I saw them bleeding one day. The vet said that she had developed a bacterial infection, and her gums would be very tender to the touch.

I had a hard time putting the numbing ointment on them, and each time I needed to medicate her, we struggled. I won in the end, though, and after the antibiotics did their job, I got to stop rubbing the ointment on her gums.


@giddion – Oh, that sounds so painful! It's good that you knew what caused the blisters, though.

I think I would have a panic attack if I saw blisters in my old dog's mouth. I know that they can indicate fatal conditions, and since she is fourteen years old, I worry about her a lot.


I once thought my dog was choking, so I was relieved to find out she had mouth blisters. She kept opening her mouth wide and pawing at it, so I held her down and saw that she had gotten a stick stuck on the roof of her mouth in between her left and right rows of teeth.

I removed the stick, but there were bloody blisters underneath. She had to take antibiotics for two weeks to get rid of them.


I knew something was wrong with my dog when she slowed down while eating. She had always eaten ravenously, but she had begun taking small bites and whining a little while trying to swallow.

I looked in her mouth and saw several blisters. Then, it hit me. She had eaten a wild citrus fruit a few days before that she had found growing in the pasture on a thorny bush.

The high acid content in the fruit must have irritated her mouth. The vet gave her some medication, and the blisters disappeared in a couple of days. I know that she was glad to be able to scarf down her food again!

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