Canine Mouth Cancer

Canine mouth cancer is the fourth most common cancer in dogs. More commonly, oral cancer in dogs tends to affect older dogs.

The oral cavity is a common area for tumor growth. Fortunately, not all oral tumors are malignant. In dogs there are various kinds of benign tumors that can grow in the mouth. Since we cannot tell whether a growth is benign or cancerous, it is important to consult a vet for immediate examination if you find any unusual growth or lesion in your dog's mouth.

Two Types of Dog Mouth Tumors

Benign Mouth Tumors

The most common benign tumor in dogs is an epulid, which is a tumor of the periodontal ligament.

In addition, other benign growths, such as fibromas, can occur in the mouth. Common characteristics of benign mouth tumors are that these tumors usually have well defined borders. Also, they do not invade the bone or other tissues, nor do they metastasize (spread). Once surgically removed, the dog patient is safe.

Malignant Mouth Tumors

There are three common mouth cancerous tumors in dogs. They are malignant melanomas, squamous cell carcinomas, and fibrosarcomas.

Melanomas are probably the most common oral tumors in dogs. Melanomas are locally invasive; they also metastasize early so by the time a diagnosis is made, the cancer has already spread to the regional lymph nodes along the neck and to the lungs. Melanomas usually appear as dark lumps inside the mouth, typically in the lower gums. They often involve the bones of the jaw as well as the gums, and are most commonly seen in older dogs. (This post by a dog parent tells us how aggressive melanomas are, and how a wrong or late diagnosis can allow the cancer to spread rapidly. Read also this post to see the importance of early treatment.)

The second most common oral tumors in dogs are squamous cell carcinomas, which are locally aggressive but they only tend to metastasize when the cancer is at a late stage. Sometimes they do not spread at all. Very commonly, they also invade the underlying bone.

Another common oral tumor in dogs is fibrosarcoma. This type of tumor is also locally aggressive but does not tend to spread. Fibrosarcomas usually appear as red growths, which can be fibrous or ulcerated, and are seen more commonly in older, male, large breed dogs.

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Signs of Canine Mouth Cancer

It is not difficult to notice if a dog has a sore mouth - usually the dog will drool excessively due to pain. He may show appetite loss or reluctance to eat due to pain and/or difficulty in eating.

If your dog shows the above two symptoms, check her mouth carefully for the following clinical signs of canine mouth cancer:

Bad breath.
Bleeding from the mouth.
Facial swelling.
Chewing on one side of the mouth.

If you are thinking that these signs are very similar to severe dental problems, you are exactly right! That's why if your dog shows the above signs, it is important to take her to a vet for a thorough oral examination immediately. Any tumors found in the mouth should be biopsied.

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Causes of Canine Mouth Cancer

It is not exactly clear as to why dogs can develop mouth cancer, but some veterinarians suspect that dogs may be able to inhale carcinogens (agents that cause cancer) while they are sniffing around. These carcinogens may be deposited in the oral cavity where they affect normal cells which eventually grow into cancerous tumors.

As well, there may be a link between dog mouth cancer and some commercial dog foods, especially those that contain chemical preservatives.

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Treatment for Canine Mouth Cancer

Depending on the type and the exact location of the tumor, several treatments are available, such as surgery, radiation, chemotherapy, and sometimes cryosurgery (freezing of the tumor).

The problem with surgery in malignant melanomas is the size of the piece of tissue that needs to be removed. Because these tumors are invasive, aggressive surgery removing not only the tumor but also at least 2 cm of normal tissue at all margins of the tumor is necessary. If the tumor occurs on the hard palate or soft palate, this may be complicated and ineffective.

A new vaccine called the Canine Melanoma Vaccine DNA is now available to treat malignant melanoma. The vaccine works by injecting a protein into the body, alerting the immune system to the presence of the melanoma tumor protein.

See the video below:

Radiation can be used to assist in local control if clean margins could not be achieved through surgery.

Chemotherapy can be used as a follow-up treatment for cancers that have spread far from the primary site.

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Natural Remedies for Canine Mouth Cancer

While natural complementary treatment options, such as herbs, homeopathic remedies, and natural supplements, may not be able to completely cure oral cancer, they can nevertheless work towards strengthening your dog's immune system, helping the body fight against cancer.

Visit our pages on Herbs for Cancer in Dogs and Dog Cancer Diet for more information on these two complementary treatment options. Please also use the navigation bar on the left of this page to find other useful K9 cancer information on this site.