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Informative Guide to Mouth Cancer in Dogs

Mouth cancer in dogs is a serious and complicated topic. There are a number of oral growths that are benign (non-cancerous) and others that are cancerous.

Unfortunately, you can’t tell which is which just be looking at it. A licensed veterinarian should always be called for diagnosis.

Diagnosing any new lump or bump in a dog generally requires a biopsy in order to examine the tissue.

Malignant Melanoma of the Oral Cavity

Malignant melanoma is one of the more common types of skin cancers in dogs. Melanoma accounts for 30% – 40% of malignancies in dogs. That sounds like a lot to me.

The interesting thing about melanoma in dogs is that it’s not thought to be directly related to increased exposure to sunlight the way it is for humans.

Instead, it’s thought to occur as a result of a variety of genetic or hereditary factors.

Survival Stats for Malignant Melanoma in Dogs

Oral melanoma is staged by the size of the tumor.

Stage I: The tumor is less than 2 cm.

Stage II: The tumor is between 2 cm and 4 cm

Stage III: The tumor is at least 4 cm and has spread into the lymph nodes.

There are many treatments including surgery, chemotherapy, and radiation therapy that can increase your dog’s survival time.

An abstract found in the 2007 May 22 (2):55-60 issue of Clinical Tech Small Animal Practice, notes that with surgery, the average survival time of dogs with mouth cancer is:

Seventeen to Eighteen Months (17 – 18) with surgery at Stage 1

Five to Six Months (5 – 6 ) with surgery at Stage II

3 Months (3) with surgery at Stage III.

Oral Squamous Cell Carcinoma – 2nd Most Common Mouth Cancer in Dogs

Squamous cell carcinoma is the second most common oral cancer in dogs and accounts for about 5% of all skin cancers.

This type of cancer is more of a risk to dogs with very short hair with more exposed skin.

Dogs who spend a lot of time in the sun may be at higher risk, although the data isn’t really clear on that.

Oral squamous cell carcinoma can look a little flaky or ulcerated. If you happen to notice a sore patch in your dog’s mouth, don’t automatically assume it’s cancer.

That’s the problem with all lumps and bumps on dogs and it’s extremely frustrating. You just can’t tell by looking. Fine needle aspiration is required so that the doctor can examine the tissue.

You should ALWAYS bring your dog to a veterinarian whenever you see anything suspicious – no matter the size or what it looks like. Before you panic, take a step back and consider any other signs and symptoms.

Have you noticed blood coming from your dog’s mouth for no apparent reason? Does your dog have trouble eating, low appetite, or seems to be eating only on one side of his/her mouth? Other symptoms of oral squamous cell carcinoma include:

Not every lump or bump signifies mouth cancer in a dog.Pin

Facial Swelling:

Sometimes red, raised gums and facial swelling with pain is caused by an abscessed tooth, not to be confused with mouth cancer in dogs.

Oral Discharge

This might include small amounts of blood mixed with saliva.


Dysphagia is a fancy word that means difficulty swallowing. You might notice your dog coughs up a little food when he/she tries to eat.

Excessive Drooling

Some dogs naturally drool a lot and others hardly at all. If your dog is suddenly drenching pillows, it might be cause for concern.

Again, it doesn’t necessarily signify cancer. There are all kinds of things that can go wrong including a variety of dental problems.


I’m sure you already know what halitosis is, but in case you don’t….it’s bad breath.

Frankly, I don’t know any dog with minty fresh breath. However, if you suddenly notice an unusual stench, have your dog checked.

A lump could be a sign of mouth cancer in dogs, but it can be any number of other things as well.

Get your dog checked by a professional and try not to drive yourself crazy with worry.

Recurrent Squamous Cell Carcinoma

Any squamous cell carcinoma has the potential to recur.

Surgery combined with radiation therapy might be one option presented to you and, generally, it works well.

I’ve read different things, but it seems that some dogs go a few years before the cancerous growth returns.

The surgery involved (depending on how involved the cancer is) involves extracting the tumor – usually along with some teeth and even a part of the jaw.


Fibrosarcoma is a slow-spreading tumor that doesn’t usually spread throughout the body. It can, however, aggressively affect the tissue/bone nearby.

Actually, “fibrosarcoma” is kind of lumped into a group of tumors and doesn’t define just one type.

From what I understand, fibrosarcoma are soft-tissue tumors that originate in the connective tissue of the skin.

Fibrosarcoma also falls within the category of a spindle cell tumor. Some pathologists only use the term “fibrosarcoma” to refer to the most aggressive tumors.

The problem with diagnosing fibrosarcoma in dogs is finding it in the first place.

Unless you are really familiar with the inside of your dog’s mouth, you may not even notice the tumor until it is well established.

Can Mouth Cancer in Dogs be Cured?

Unless the tumors are in places nearly impossible to operate, oral surgery combined with radiation therapy can increase survival time.

As noted above, survival times are directly tied to the staging of the cancer.

Until your dog has undergone surgery and has been assessed by a canine pathologist, it’s impossible to give you a specific life expectancy.

In order to determine the cancer “grade”, a veterinarian pathologist (or possibly another veterinarian professional) will want to do a fine needle aspirate and possibly a CT scan.

The reality is, there’s no cure for cancer and some cancers are “better” than others.

All sorts of things will affect survival time including the overall health of your dog (before cancer), age, and availability of treatment options.

Cancerous tumors can appear on various parts of the body. However, oral tumors (or oral mass) are typically seen on the dog’s lips, tongue, gums, and lymph nodes.

The Price-Tag Reality

Unless you have pet insurance that covers cancer treatments including surgery, chemotherapy, and radiation therapy, you could be looking at a cost upwards of $5000 or more.

Not everyone can afford that, and nobody should feel guilty about it.

It is a tough decision to make and a completely personal one. Some things to consider when deciding whether to go ahead with canine cancer treatments include the following:

Dog’s Age

A dog is considered to be entering the senior years by age 7.

Smaller dogs generally live longer than large dogs. If your dog is in his/her senior years, you may opt for palliative care.

Palliative care involves any number of things to reduce pain and discomfort.


How often are you going to have to go through this? I think this is a question that a good canine pathologist could answer.

They know the statistics and might be able to give you a reasonable time-frame.


Obviously, you’ll need to determine if you can afford the treatment options presented.

We all want to preserve our dog’s life as long as possible, but at some point you have to make some tough decisions.

Luckily, there are veterinarians who offer payment plans. There’s also nothing wrong with shopping around for the best price. It doesn’t make you a bad person.

When It’s NOT Cancer

Papilloma Virus

It’s important to remember that there are other sores, lumps and bumps in a dog’s mouth that are not cancer.

For example, papilloma warts are benign, contagious tumours.

Dogs who share water bowls, toys, or greet other dogs by the mouth are at risk of developing these growths. Remember, they are not cancerous.

Some people might mistake dog warts for dog mouth cancer.Pin
Papilloma warts are benign but contagious tumours.

A papilloma wart looks like a little like cauliflower and can occur anywhere in the dog’s mouth. The only treatment for these is time.

Eventually, they will usually resolve on their own. In the meantime, however, it could mean keeping your dog out of the park for a while.


Unless your dog has regular, professional dental care, there’s a good chance he or she will develop gingivitis.

Plaque and tartar buildup leave the gums vulnerable to bacteria, and that bacteria quickly turns into a full-blown infection.

Like cancer, your dog may develop a swollen muzzle, drool more often, and loses his/her appetite.


An epulis is a benign tumor that develops in the ligament that holds the tooth into the jawbone. These tumors are very common in dogs over the age of six.

At The End of The Day…

The most commonly found lump in a dog’s mouth is the benign epulis. They are pinkish in appearance, develop on the gumline, can be fast or slow growing, and are firm to the touch.

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