yorkie opening its mouth

Question: My dog has a black mole in his mouth that is growing. Should I be concerned?

My dog Maverick has a mole in his mouth that is increasing in size as he grows older. Should I have it checked out?


Closeup of a dog's face who has his mouth open showing a mysterious black spot on their gums


Dear Michael,

Thank you for submitting your question about Maverick! Anytime that you notice a change in your pet, I think it is a good idea to get it checked out by a veterinarian. Flat black spots on dogs’ gums can be normal, but it would be a good idea to confirm that it is a normal spot with your veterinarian, especially since it has been growing in size.

Sometimes, these flat black spots can grow in size normally as a dog gets older. Occasionally, black spots on the gum can be a sign of something worse. Black spots that are raised or growing in size could be a sign of melanoma, a type of oral cancer, but this is less common especially in a young dog. I will describe what can potentially cause black spots on a dog’s gums and what you should do about it.

What Causes Black Spots in a Dog’s Mouth?

1. Normal Pigmentation

Most often, a black spot in a dog’s mouth is caused by normal pigment. Melanin is a naturally occurring pigment that can cause areas of the skin, gums, nose, or tongue to appear black. These spots will be flat and typically don’t change in size. Occasionally, as a dog gets older, these flat black spots can grow in size, but the growth is usually slow. These spots are considered normal, similar to a birthmark or freckles in people, and may be more common in certain dog breeds. The Chow Chow and Shar Pei are two breeds known for black spots in the mouth.

2. Oral Melanoma

Oral melanoma is another cause of black spots on a dog’s gum. This is a type of malignant mouth cancer. Usually, melanoma will appear as a raised lesion on the gums. Melanoma lesions will continue to grow over time, and you may also notice foul breath or an odor coming from your dog’s mouth.

3. Dental Disease

Dental disease can also darken the gums of a dog. These dark spots can appear on the gum around where there is an infected tooth or dental disease. Other signs of dental disease include tooth loss, foul breath, and tartar build-up. To maintain healthy teeth, it is a good idea to brush your dog’s teeth daily with a dog-specific toothpaste and soft-bristled toothbrush.

When Should I Take My Dog to the Vet for Black Spots on the Gums?

Anytime you notice a change in your dog, it is a good idea to speak with a veterinarian. I think is especially important to get a black spot on the gums checked out if it is:

  • Growing in size
  • Raised
  • Painful
  • Stinky
  • Causing any other symptoms

Final Thoughts

Most commonly, flat black spots on the gums are normal areas of dark pigment. Usually, these spots stay the same size, but occasionally, they can grow as your dog gets older. Rarely, black spots can be caused by more serious issues like melanoma or dental disease. Because your dog’s black spot on the gum has been growing in size, I think it would be a good idea to get it checked out by your veterinarian just to be safe. Good luck with your sweet pup, and thanks so much for sending in your question.


Addie Reinhard, DVM

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