If your dog was diagnosed with a malignant melanoma in the mouth, you may be wondering about oral melanoma dog life expectancy. When it comes to dog cancer, life expectancy is difficult to estimate because there are many individual factors such as how long the melanoma has been there, its size and whether the cancer has spread to other body parts. As with many other types of cancer, early intervention when the oral melanoma is still small in size, has a better outcome in oral melanoma dog life expectancy compared to advanced cases.
A Word about Prognosis
Prognosis is a medical term used to depict the future course of a disease and the chances the dog has for recovery. A prognosis is made by looking at statistical data that has been collected by researchers over many years regarding dogs suffering from the same type of cancer.
While looking at statistics of dogs suffering from the same type of cancer and their outcome, because of the interplay of many other individual factors, coming to an exact life expectancy for dogs with cancer is very difficult. Every dog is different and the way the individual dog responds to treatment is something that can be difficult to predict.
However, by factoring in your dog's individual situation and by looking at what research says, your vet may be able to make an educated guess about how likely your dog is to respond well to treatment and roughly how long he may be expected to live. With this in mind, it's important to recognize though that no vet will be able to tell you with certainty how things will go exactly for your dog.
"You must realize that stats will never predict the individual. I personally hope your pet outlives the stats, but my advice — after all my training and years of clinical experience — is this: Learn the facts, and then be hopeful."~Dr. Susan Ettinger, veterinary oncologist.
Oral Melanoma Staging
On top of looking at statistics of survival times of dogs suffering from oral melanoma cancer, staging is something veterinarians do so to have a better insight on the dog's chances for survival. Staging means putting together several factors and categorizing the cancer accordingly.
Staging is often based on the World Health Organization (WHO) staging system and can provide an insight on prognosis, even though, as mentioned, estimates on dog life expectancy cannot be considered accurate. In the case of an oral melanoma, significant factors include where the cancer is located, how large it is, whether the nearby lymph nodes are inflamed, whether the cancer has spread to other organs, and what the pathology findings reveal.
It is therefore important for staging purposes having the dog undergo a throughout physical examination, blood tests, chest x-rays and having tissue sent out to a pathologist to determine how aggressive the cancer is. From staging, several prognostic factors can be deduced.
Some Prognostic Factors
Staging takes into consideration several prognostic factors and can provide an insight on survival times. For instance, when it comes to melanomas, location is an important consideration. Studies have found that melanomas found in hairy areas of dogs have a better prognosis (most are benign!) than melanomas found in the dog's nail bed or mouth.
Size is also an important prognostic factor. Oral melanomas that are less than 2 centimeters are categorized as stage 1 oral melanomas, whereas, melanomas that are anywhere between 2 and 4 centimeters are categorized as stage 2.
Oral melanomas are very likely to metastasize (spread to other body parts). Whether the dog's local lymph noses are involved or not, can also be a prognostic factor. The vet will palpate the dog's lymph nodes under the jaw and a CT scan or ultrasound can show whether there is involvement of the parotid and retropharyngeal lymph nodes. Tissue biopsy of lymph nodes sent out to a pathologist can also reveal whether the cancer has spread.
Further spread of cancer to vital organs can be assessed but taking chest x-rays. The x-rays can show whether the cancer has spread to the dog's lungs. Spread to the lungs is seen as a late sign of oral melanoma. A CT scan may provide a more accurate picture of the lungs.
Finally, a biopsy followed by a pathology report of the mass can provide a definite diagnosis confirming or ruling out oral cancer and revealing its aggressiveness. This is done under general anesthesia.
Life Expectancy of Dog Oral Melanoma
In dogs with oral melanoma, the size and stage of the disease can have a significant impact on life expectancy. Treatment of oral melanoma in dogs requires surgical removal of the mass, and in more severe cases, removal of part of the jaw (partial or complete mandibulectomy, maxillectomy).
Generally, dogs with stage 1 oral melanomas that were measuring less than 2 cm and that had not spread, had a medial survival time of 17 to 18 months following surgical removal.
Dogs with stage 2 oral melanoma measuring between 2 and 4 cm that had not spread had a median survival time of 5 to 6 months following surgical removal.
Dogs with stage 3 oral melanoma that was larger than 4 cm and that had spread to the local lymph nodes, had a median survival time of 3 months, while dogs with stage 4 which had spread to the lungs, had only a few weeks to months.
If your dog has oral melanoma, consider that consulting with a veterinary oncologist is important as survival times may be increased through radiation treatment and other options such as a melanoma vaccine which seems promising in terms of survival. Only through your vet or veterinary oncologist you can attain a more accurate picture about survival times for your best friend.
"So far the data has shown median survival times for melanoma with the use of the vaccine is as follows: Stage I > 939 days with 92.8% survival, Stage II > 908 days with 79% living 1 year and 63% living 2 years, Stage III > 1646 days with 77% living 1 year, 65% living 2 years and 57% living 3 years. Stage IV = 293 days with 40.5% living 1 year and 18.8% living 2 years." ~Dr. Laura Devlin, veterinarian
- The histologic and epidemiologic bases for prognostic considerations in canine melanocytic neoplasia. Spangler WL, Kass PH. Vet Pathol 43:136-149, 2006
- Esplin DG. Survival of dogs following surgical excision of histologically well-differentiated melanocytic neoplasms of the mucous membranes of the lips and oral cavity. Vet Pathol. 2008 Nov;45(6):889-96.
- Williams LE, et al. Association between lymph node size and metastasis in dogs with oral malignant melanoma: 100 cases (1987-2001). J Am Vet Med Assoc. 2003 May 1;222(9):1234-6.
- Clinician Brief, Staging Melanoma of the Oral Cavity or Skin in Dogs
- Clinical Appearance of Melanotic Melanoma, Source Vetpedia: http://www.vetpedia.net/siteen/content/tumours-oral-cavity