Melanomas arise from the pigment-producing cells called melanocytes. Most commonly these tumors are dark-colored, firm nodules that are locally invasive and often metastasize readily. Some melanomas, however, are not dark in color so appearance alone is not 100% predictable. One of the more common tumors in domestic animals, melanomas can have a variety of clincal behaviors depending on species and location of the tumor.
Melanomas are commonly seen in grey horses especially around the anus. These tumors tend to be locally invasive and recur once excised but rarely metastasize to other part of the body and rarely cause problems aside from functional problems to defecation
Melanomas are the most common oral tumor in dogs and the third most common oral tumor in cats. These tumors are locally invasive and metastasize quickly to regional lymph nodes. Radical excision including part or all of the jawbones will give a average survival time of 1 year if all the tumor is excised and 9 months if only part of the tumor is removed. In cats, survivial is less than 60 days regardless of the amount of surgical excision. Radiation and chemotherapy are inconsistent in their results and on the whole do not appear to significantly prolong survival time.
Melanomas are also common tumors of the skin and digits in dogs and cats. These are most often malignant but can be benign. They are also typically locally invasive but as a whole slow to metastasize (ones on the digit are more likely to metastasize). Metastasis is usually to the local lymph nodes, bones, lungs, and abdominal viscera.
Any lump or nodule should be examined by your veterinarian to determine if surgical excision and histopathologic analysis is indicated
For more information, please contact your veterinarian or email me..