Key takeaways
Melanoma is a tumor which develops from the cells responsible for skin pigmentation (melanocytes).
- Melanomas can be either benign or malignant and can be found on the skin, mouth, and eyes
- Melanoma is a common type of tumor and melanomas of the skin are more often seen in dog breeds with dark skin
- Melanoma of the skin is most often benign, with the exception of melanoma of the toe, which is very aggressive
- Oral melanoma is often aggressive and metastatic
- Uveal melanoma is uncommon but when present is often locally aggressive but not malignant
- Diagnostics include imaging, blood work, biopsy, and cytology of the tumor
- Treatment varies but can include surgery, radiation, cryotherapy, and palliative care
- Prognosis is good in cases of benign tumors
- In the case of aggressive or metastatic tumors, prognosis is poor
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A closer look: Melanoma in Dogs
Any pigmented mass should be evaluated by a veterinarian in a timely manner.
The physical appearance of melanomas can vary widely and depends on the location. Melanoma can occur as a single tumor or multiple, tends to be small in size (0.5cm-4.0cm), and can be flat or raised. Other symptoms vary depending on location and the extent of tumor size and spread.
Symptoms may vary depending on tumor location.
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Risk factors
Melanoma is a common type of tumor in dogs and can be divided into three main categories which can have different risk factors and behaviors.
Cutaneous (skin) tumors are most often benign and are common.
Uveal (eye) tumors are uncommon overall but are the most common type of primary eye tumor in dogs. These are usually benign but can be locally invasive, destroying the structures of the eye.
Oral melanoma is common in dogs and much more likely to be aggressive and metastatic.
Dog breeds with dark skin are at higher risk of developing melanoma, and it is more likely to be malignant in older dogs.
As will all forms of cancer, genetic and environmental predisposing factors are likely.
Possible causes
The cause of melanoma is currently unknown. It is not shown to be caused by UV exposure as it is in humans. However, constant irritation may play a role in the development of cutaneous melanoma.
Main symptoms
The main symptom of melanoma is a mass, generally brown or black, but sometimes pink, anywhere on the body. Some common areas melanomas may appear are the toes, in the mouth, lips, and the eyes.
Testing and diagnosis
Diagnostics to confirm melanoma and to determine metastasis include:
- Diagnostic imaging
- Blood work
- Evaluation of cell samples from the tumor (biopsy and cytology)
Steps to Recovery
Once melanoma is confirmed, there are a number of treatment options:
- Surgical removal
- Radiation
- Chemotherapy
- Cryotherapy
- NSAIDs (anti-inflammatory pain killers)
- Topical medication
- Palliative care
- Vaccination for the oral form
- Vaccination for the cutaneous form (experimental)
If the tumor is benign and complete surgical removal is possible and performed successfully, prognosis is generally good with monitoring for recurrence.
Cutaneous melanomas around the lips, eyelids, and toes generally have a poorer prognosis and are more often aggressive tumors.
In the case of aggressive or metastatic tumors in general, prognosis is poor even with treatment.
Prevention
As the cause of melanoma is not known, prevention is not currently possible. Regular monitoring of overall health and changes in the skin, eyes, and mouth can allow for tumors to be identified earlier in development and may allow for treatment before metastasis begins.
Melanoma is not contagious.
Is Melanoma in Dogs common?
Melanoma is common in dogs.
Typical Treatment
- Surgical removal
- Radiation
- Chemotherapy
- Cryotherapy
- NSAIDs
- Topical medication
- Palliative care
- Vaccination for the oral form
- Vaccination for the cutaneous form (experimental)
