from the Vet Corner Archives
Part of Horse Previews Magazine website. Posted on 01/01/99; 2:00:00PM.
Veterinary Corner 1/99: Sarcoids
by Frosty Franklin, DVM
Edgecliff Equine Hospital
S. 1322 Park Road, Spokane, WA 99212 * 509/924-6069
In the last few weeks clients have asked many questions about sarcoids. What are they? What causes them? Are they contagious? Is there anything I can do about them? How can I prevent my horse from developing sarcoids? These numerous questions have prompted me to write this month's article on the subject of equine sarcoids.
Equine sarcoids are the most frequently seen equine tumor. They are a locally aggressive, benign (non-cancerous) fribroblastic tumor of the dermis and epidermis (skin). Any horse is susceptible to sarcoid development as there is no connection with breed, sex, or coat color. It is most common to see them in middle-aged horses, but a horse of any age can be affected. Areas most frequently involved include the skin of the head (eyelids, ears, and mouth), tailhead, legs, and ventral trunk or any sites that have been previously traumatized.
Two types of equine sarcoid have been clinically identified. The verrucous type has a dry, wartlike appearance, and is usually small and flat. It may remain unchanged for many years and will occasionally regress spontaneously. They can, however, develop into the more aggressive fibroblastic type. This type of sarcoid can either appear as firm nodules in the dermis covered with normal epidermis or as large masses with ulcerated surfaces. They can be invasive and destructive and can rapidly advance into large, proliferative masses.
It is thought that sarcoids are virally induced. Both papillomavirus and retroviurs particles have been identified in equine sarcoids. It is also thought that a predisposition to develop sarcoids may be familial. They are not believed to be contagious.
Treatment of sarcoids varies depending on the size, location, and aggressiveness of the lesion. Surgical excision combined with cryosurgery using a two freeze-thaw cycle is generally the treatment of choice. The tumor may need to be retreated at specific intervals, but a tumor control rate of approximately 70% can be achieved using this technique. Good communication with your veterinarian concerning the tumor's status can ensure that the sarcoid is treated at appropriate intervals.
Another treatment option is injection with a commercially available immunostimulant like Regressin-V. This treatment stimulates the horses own immune system to recognize the tumor and attack it. In a horse that has multiple sarcoids, this type of treatment may cause untreated sarcoids to regress as well. This treatment is especially helpful in cases where the sarcoid is in an area where surgical excision and cryotherapy are difficult or in cases where cosmetically superior results are desired, such as in a show horse.
Currently, there are no vaccines or scientifically proven techniques that will prevent sarcoids. However, early recognition and treatment almost always make treatment more successful with fewer needed treatments and less expense.
If you suspect that your horse has a sarcoid, please call your veterinarian so he or she can do a thorough exam and give you a specific diagnosis. The veterinarian can then offer advice about the appropriate course of treatment. My staff and I hoped you all had a happy and safe holiday.
Happy Trails & Happy New Year