Case 7: Sarcoid

Sarcoids are the most common skin tumor of horses.  Although they are considered benign in that they do not spread to other organs of the body, they can present serious problems with tack interference, discomfort, flies, and cosmetic appearance.

This month’s case follows Susie, a 20-year-old Percheron/Thoroughbred cross during her treatment for a particularly aggressive sarcoid on her ear.  Treatment for sarcoids comes in many different forms, both conventional and non-conventional with varying reports of success.  These include surgical excision, cryosurgery, radiation, immunological methods, multiple chemotherapeutic agents, and combinations of the above.  When a laundry list of treatment options exists for a single clinical problem, usually one of two things are at play, either no one treatment works all of the time or some treatments come with severe restrictions.  With sarcoids, both of these hold true.

  Susie was 17 when North Florida Equine started treatment.  At this time, several different methods had been employed to treat the multiple lesions on her ear, none successfully.  Susie’s ear was heavy with tumors; she couldn’t even hold it upright.  It oozed and attracted flies and seemed to bother her constantly.  This picture was taken of Susie’s ear on the first day of treatment:

Sarcoids - the most common skin tumor of horses (1)

That day, Susie was put under general anesthesia.  Dr. Tanhauser then surgically removed as much of the tumors as possible.  Here is Susie’s ear after surgery:

Sarcoids - the most common skin tumor of horses (2)

Sarcoids are notorious for quickly regrowing if surgical removal is the only treatment performed; occasionally, they can even become more aggressive after surgical manipulation!  The anatomical restrictions of the ear also made it impossible to remove all of the tumor tissue.  Knowing this, Dr. Tanhauser followed the tumor removal with the implantation of 24 tiny cisplatin beads.  Cisplatin is a chemotherapeutic agent used to treat skin tumors in horses; it can be injected as a liquid or used in the form of small beads that are embedded into cancerous tissue. The cisplatin beads are very small, as you can see in the picture below, and multiple beads are required for even a small treatment area.

Sarcoids - the most common skin tumor of horses (3)

Implanting these tiny beads is time consuming, and this ear was so severely affected that it would require many, many beads.  Due to concern about lengthy anesthesia, a second surgery was planned one week later to implant 27 additional beads.  Susie was also placed on a course of antibiotics and an anti-inflammatory medication.

One month later, there was such dramatic improvement that Susie’s owner was anxious to continue treatment:

Sarcoids - the most common skin tumor of horses (4)

Susie was again anesthetized for treatment. You can see in the picture above that some of the treated tumors had regressed, but were not completely gone, and others, due to the overwhelming number of tumors present at the initial surgery, had yet to be addressed.  27 more cisplatin beads were implanted that day.

Approximately six weeks later, additional tumors at the base of the ear were surgically removed (the sutures are visible on the picture below) and another 24 beads were implanted.

Sarcoids - the most common skin tumor of horses (5)

Ten months after beginning treatment, most of the tumors that had been removed and treated remained quiet; a few became active (picture below) and these were treated with the implantation of 15 cisplatin beads.

Sarcoids - the most common skin tumor of horses (6)

Four and a half months later, a few active tumors were developing and they were treated with the implantation of 7 beads.  Two months later a final treatment with the implantation of 11 beads was performed.

In all, 124 cisplatin beads were implanted over a period of about 16 months.  The tumors appear gone or inactive; with a few nodular tumors remaining at the base of the ear. One year after her final treatment, Susie is still doing well.

Sarcoids - the most common skin tumor of horses (6)

After Treatment

Sarcoids - the most common skin tumor of horses (1)

Before Treatment

Sarcoids can take on several different forms including the superficial types of the occult sarcoid (which looks like an area of hair loss, left picture) and the verrucose sarcoid (which looks like warty skin, right picture).

(the following six pictures are from 2009 Elsevier Ltd. Knottenbelt: Pascoe’s Principles and Practice of Equine Dermatology 2e)

Sarcoids - the most common skin tumor of horses - occult

Occult Sarcoid

Verrucose Sarcoid

Verrucose Sarcoid

There is also a nodular type, which can be found as multiple or single lesions:

Nodular sarcoids 2

Nodular sarcoids

Nodular sarcoids

Nodular sarcoids

Susie’s case was an example of the more aggressive fibroblastic sarcoid. These have a characteristic fleshy, ulcerated appearance and often acquire secondary infections.  These are easily traumatized and often bleed or ooze serum, becoming a big problem with flies.  Other sarcoid types can morph into the more aggressive fibroblastic type if they are traumatized by injury or with unsuccessful attempts at surgical removal.

Fibroblastic sarcoid

Fibroblastic sarcoid

A combination of types also occurs.  The lesion below has characteristics of a verrucose, nodular and fibroblastic sarcoid.

Mixed sarcoid

Mixed sarcoid

Susie is an amazing success story, as sarcoids can be very frustrating to treat.  Her ear has gone from a debilitating problem to something a casual observer wouldn’t even notice today.  It is important to remember that although sarcoids are generally not life threatening, the prognosis for a complete cure is guarded.  Once a horse has been affected with sarcoids they seem to be predisposed to developing additional tumors or having a reoccurrence of once quiescent lesions. Reoccurrence can take place from days to even decades after treatment.  Susie’s owners will continue to keep a vigilant eye, but for now Susie is comfortable and happy!

North Florida Equine Veterinary Service Gainesville Newberry Ocala Florida - Susie