If sarcoids removed using laser surgery don’t recur within six months they are likely gone for good, according to a new study from England.

Medical lasers are now used for several types of surgery because their incisions bleed less during procedures and heal with less swelling and pain afterward. Sarcoids are tumors of the skin that are usually benign but can be persistent and locally invasive.

Working at Rossdales Equine Hospital, researchers reviewed the records of 99 horses who had a total of 235 sarcoids removed using neodymium-doped yttrium aluminum garnet lasers to cut away the tumors and surrounding tissues.

For each case, the researchers collected information about both the horse and the tumor, including the size and location of the sarcoid and time of year it was removed. They also noted details about the surgery, such as whether tumor-free margins were confirmed with a microscope. Follow-up interviews with owners were then conducted to find out if the sarcoid at the surgical site had reappeared or if new ones developed elsewhere on the horse’s body.

The appearance of sarcoids on other areas of the body is relevant “because there is anecdotal evidence that a sarcoid in one location may predispose a horse to tumors elsewhere,” says Polly Compston, MRCVS, BSc, BVM&S. “Such is the weirdness of sarcoids. We don’t have a clear idea of the risk factors for their development. The mantra with sarcoids is to expect the unexpected.”

The data showed that 83 percent of the horses had no recurrence of the sarcoid at the surgical site and 72 percent had no recurrence of sarcoids anywhere on the body after surgery. This success rate is slightly lower than methods that use certain chemotherapy agents or radiation, but the researchers note that laser therapy is often cheaper, easier and safer for both the horse and surgeon.

Overall, 195 of the sarcoids were successfully treated, while 40 recurred at the same location, and in 28 cases tumors developed in new locations subsequent to surgery. The data also showed that sarcoids on the head and neck were most likely to reappear. In addition, recurrence was slightly more likely if the horse had at least one verrucose sarcoid (those that have a more “warty” appearance) anywhere on the body. Horses previously treated for sarcoids, whether by their owners with a topical cream or under the supervision of a veterinarian with creams or cryotherapy, had a higher risk of recurrence after laser surgery.

Compston says that the six-month time frame for sarcoids to recur is a significant finding of the study: “It goes along with anecdotal clinical experience that some horses have a sarcoid that once removed is gone for good, while others have a more systemic pathology that is much harder to manage.”

Her advice for those whose horses have sarcoids is to be proactive but realistic. “Talk to your vet, and discuss laser surgery, especially if there’s only one sarcoid and it’s in an amenable location,” she says. “Accept that your vet cannot guarantee a cure for any horse with a sarcoid. If there are lots of sarcoids, your horse is unlikely to become sarcoid free.”

Reference: “Laser surgery as a treatment for histologically confirmed sarcoids in the horse,” Equine Veterinary Journal, May 2015

This article first appeared in EQUUS issue #456

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