Although most sarcoids in horses are not malignant, they can be unsightly and in many cases disfiguring, while causing the horse discomfort. New research shows that sarcoids may be the first cross species papillomaviral infection.
Commonly found on the legs, abdomen, head, and around the eyes of horses, sarcoids vary in size from less than an inch to several inches in diameter. While no definitive cause has been identified, DNA studies have linked equine sarcoids to Bovine Papilloma Virus, Types 1 and 2.
Now, new research shows that the disease is associated with BPV-1/2 infection and that sarcoids represent the first known natural cross species papillomaviral infection. Current projects are aimed at furthering the understanding of the viral pathogenesis of sarcoids by studying the mechanisms by which viral infection can induce cell transformation and cell invasion and interactions of the virus with host cell defenses.
Researchers are attempting to understand the infectious nature of the disease and the mechanisms of disease transmission. They are actively engaged in evolutionary studies of the worldwide distribution of BPV variants in equines and bovines.
The distribution of the lesions leads researchers to believe that flies and viruses are involved, but no definite link has been established. DNA studies suggest that equine sarcoids are caused by the cattle wart virus Bovine Papilloma Virus, Types 1 and 2.
Although sarcoids do not extend into internal organs, when sarcoids are successfully treated, both the behavior and performance of horses noticeably improve, suggesting that chemical products from the sarcoids may have internal consequences for the horse.
To date, no method of preventing the development of sarcoids has been proven effective. Good horse management, including fly control measures, may help. Some evidence suggests that thinner-skinned breeds, such as Arabian horses, have a greater tendency to develop the condition. Mares diagnosed with sarcoids should not be used for breeding purposes.