The Role of Bovine Papillomavirus in Equine Sarcoids

Bovine papillomavirus (BPV) has long been suspected of playing a role in the development of sarcoid tumors in horses. Different subtypes of the virus, BPV-1 and BPV-2, have been identified in individual sarcoid biopsies. It is not clear, however, whether BPV is present in all sarcoids. It is also unknown if the virus is found in other equine skin tumors or even in normal skin. A recent study from the University of California, Davis, attempted to answer these questions by looking for BPV DNA in biopsies of sarcoids and nearby normal skin from 55 affected horses. An additional 22 horses without sarcoids were sampled for comparison, as were several non-sarcoid skin tumors.

Almost every sarcoid tumor examined (98%) contained BPV DNA. Fifty-five percent of horses with sarcoids had sarcoids with BPV-2, while 20% of those horses had BPV-1, and 7% had both types of BPV present. More surprising was the finding that 63% of samples of normal skin from these horses contained BPV DNA. All of the biopsies from horses without sarcoids, as well as biopsies of other non-sarcoid tumors, were negative.

These findings suggest that BPV not only plays a role in sarcoid development, but is also capable of existing in a latent, non-virulent phase in normal skin. This might help explain why surgical removal of sarcoid tumors is rarely successful. Surgery might actually trigger the virus to leave the latent phase and begin formation of new sarcoids.

American Journal of Veterinary Research, 62(5), 741-744, 2001.

Editor's Note: No research has suggested any risk of sarcoids from housing horses with cattle or on land previously inhabited by cattle.

About the Author

Susan Piscopo, DVM, PhD

Susan Piscopo, DVM, PhD, is a free-lance writer in the biomedical sciences. She practiced veterinary medicine in North Carolina before accepting a fellowship to pursue a PhD in physiology at North Carolina State University. She lives in northern New Jersey with her husband and two sons.

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