Researchers at the Marion DuPont Scott Equine Medical Center, Virginia-Maryland Regional College of Veterinary Medicine, reported the results of a new approach to equine skin tumors in the Journal of the American Veterinary Medical Association.
A total of 59 equidae were diagnosed with a variety of skin tumors. They were treated by the implantation of slowly biodegradable beads containing the chemotherapy drug cisplatin. Surgery to reduce the size of the tumor was done in 76% of the animals.
Of the 48 subjects available for long-term follow-up after two years, 40 were tumor-free, no relapses. Response rates by tumor type included: 85% for sarcoids, 60% squamous cell carcinoma, 93% melanomas. No difference in relapse was found between the test subjects that did or didn’t have surgery first.
Prior to this, a 1994 study done at the University of California Davis followed treatment results in 16 sarcoids, 6 carcinomas and 1 hamartoma following surgery and follow-up injections of the tumor site with cisplatin at two-week intervals for four treatments. With that protocol, there was an average relapse-free interval of 41 +/- 3.7 months. The tumor-free percentage at one year was 92 +/- 5%, and at four years was still high at 77 +/- 11%.
Cisplatin is a salt of platinum. In the 1960s, researchers looking at the effect of electrical fields on bacterial multiplication and division discovered it wasn’t the electricity preventing bacteria from dividing, but cisplatin being given off by their electrodes.
The results of these studies and the good response rates even without surgery should make this option a more affordable choice for owners of horses with skin tumors.
