Malignant melanoma in the foot of a horse.

The researchers document a case of a 24-year-old horse diagnosed with malignant melanoma on its forefoot. Although surgery could not completely remove the cancerous growth, a therapeutic implant was used to target the remaining part of the tumor. The horse remained disease-free for over two years before the melanoma recurred, at which point it was euthanized due to the extensive spread of the disease.

Research Context

• This research focused on a single case study of a horse diagnosed with a malignant melanoma (a type of skin cancer) on its forefoot.
• The advanced age of the horse (24 years old) may have contributed to the development of the disease.

Treatment Application

• The primary method of treating the melanoma was surgical excision. However, a histologic examination revealed that the surgery did not completely remove the tumor.
• To address the remaining tumor sites, the researchers injected the margins with a matrix therapeutic implant containing cis-diamminedichloroplatinum (a chemotherapy drug), epinephrine (to constrict blood vessels and boost the effect of the chemotherapy), and a purified bovine collagen matrix (to facilitate healing).

Post-Treatment Outcome

• Following treatment, the foot healed and the horse showed no clinical signs of the disease for a considerable period — 26 months.
• Nonetheless, after this period, the malignant melanoma recurred. Upon examination, it was found that the disease had extensively invaded the foot.

Conclusion

• Due to the widespread disease, the horse was euthanized.
• This research underscores the potential for malignant melanomas to recur after treatment, even when using targeted therapy to attempt to eliminate the margins of the tumor.
• Further work would need to be conducted to improve recurrent rates and extend the disease-free survival period in similar cases.