4 Most Common Cancers in the Mouths of Cats & Dogs by Dr. Rittwage

Written by Dr. Chantal Rittwage

If the mass is in the front of the mouth, most owners will notice it.  If the mass is in the back of the mouth or under the tongue, you may see  drooling (+/- blood tinged), loose teeth, swelling of the face or bulging eyes, nose bleeds, weight loss, bad breath, difficulty eating, or even pain when he/she opens her/his mouth.  Similar signs can be seen with oral inflammation (see separate blog).

1. Malignant Oral Melanoma

To the everlasting amusement of my 3rd year radiology class, malignant oral melanomas are “. . . the worst thing you could possibly have in your mouth, well . . . maybe not the worst thing” – Dr. LeeAnn Pack.  This is an aggressive cancer that is rare in cats, but is the #1 oral cancer in dogs.  These tend to be small raised ulcerated tumors with or without black spots, typically involve the bone underneath and will commonly spread very quickly to surrounding glands and organs.

2. Oral Squamous Cell Carcinoma

This is the most common mouth tumor in cats and the second most common in dogs.  In cats these can be found in the back of the mouth or throat, but are more likely to be on the tongue.  In dogs, they tend to be in the front of the mouth on the lower jaw.  These look like red, bloody cauliflowers and are locally very aggressive.

3. Oral Fibrosarcoma

This is less common in both cats and dogs, but make up about 15% of mouth tumors.  These usually grown off the gums or hard palate (dogs) and have a flat, firm, red, ulcerated appearance.  In dogs, these will usually involve the bone but only rarely spread to the rest of the body.

4. Acanthomatous Ameloblastoma (aka: Epulis)

These are actually pretty rare in cats, but do happen.  In dogs, they make up about 5 % of all mouth tumors.  If you see a mass in the mouth this is what you cross your fingers for; because it’s BENIGN!  They typically grow from the bottom jaw along the gums in the front of the mouth and can look just like everything else, but they don’t spread to the body and they respond great to surgery.

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Pretty much, everything looks the same.  Even really bad periodontal disease can look like some of these.  Which means that biopsies, sampling the local lymph nodes, and maybe even skull X-Rays are extremely important to the diagnosis and can mean the difference of having a few months, to years to live. 




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Last updated: December 16, 2020

Dear Clients,

With recent changes to restrictions on businesses, we are pleased to advise that effective May 4, 2020 the restrictions on veterinary practices have been lifted. Based on these changes, below are some important updates to our operating policies.


This includes vaccines, wellness exams, blood work, heartworm testing, spays and neuters, dental services, and more!



We are OPEN with the following hours:

Monday, Tuesday, Wednesday and Thursday: 8:00 am - 8:00 pm
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Thank you for your patience and understanding and we look forward to seeing you and your furry family members again!

- Your dedicated team at Mountain Road Animal Hospital