A Virus Might Help Horse Wounds Heal

Your horse just found the only loose fence board in his pasture. Of course, he ripped it off the fence, cutting open his leg in the process. Being a horse owner, you’re well-acquainted with how long it takes skin to heal and how difficult it is to keep it clean and safe from infection. After all, you wouldn’t want to expose it to any viruses, right?

Well, maybe. A group of researchers from Canada and New Zealand have recently learned that a “secret agent” to enhance healing might exist in the most unlikely of places—a virus. Specifically, the “orf” virus, a parapoxvirus that causes a highly contagious skin disease in ungulates (hoofed animals) and humans.

It might sound like mad science, but the concept is perfectly safe and very promising, said Christine Theoret, PhD, DMV, Dipl. ACVS, director of the Comparative Veterinary Tissue Healing Laboratory in the Department of Veterinary Biomedicine at the University of Montreal, in Quebec, Canada.

But before you go looking for ways to smear viruses directly into your four-legged’s leg wounds, hold your horses! It’s important to note that the researchers didn’t apply the virus itself to the wounds, but rather specific proteins from the orf virus. And equally important, they still kept the wounds as clean and protected from infection as possible.

“Recombinant proteins (IL-10 and VEGF-E), derived from the virus, were used to treat the wounds,” Theoret said. “There is no risk of viral infection.”

Previous studies have shown that these two proteins worked well in the skin cells and wounds of mice, so Theoret and her fellow researchers tested the proteins’ effects in equine skin cells in a laboratory. The results, she said, were encouraging.

“Our in vitro study confirmed our hypothesis that equine skin cells express the receptors required to respond to viral IL-10 and VEGF-E,” she told The Horse.

The research team then determined the dose of the proteins that should work in horses, based on their studies in mice, and tried it on four horses. The horses—all retired Standardbreds—received experimental wounds (under local anesthesia) on their legs and body. The researchers treated half the wounds with their experimental treatment and left the other wounds clean but untreated.

Despite the success of their laboratory (in vitro) study, the wounds in the live horses did not appear to heal any faster with the treatment than without, Theoret said. However, the treated wounds did show improvements in the expression of certain genes (like for inflammation and immune responses) that suggest the viral proteins were having a positive effect on the healing process—even if it not visible to the eye. The problem, she added, was most likely related to a treatment dose that was too low to change the time required for healing.

“At this point we’ve decided to move back to in vitro testing to fine-tune our dosage regimen in the context of wound healing and other types of fibroproliferative (scarring of connective tissues such as skin, tendons, and corneas) disorders in horses,” Theoret said.

The study, “Short-term treatment of equine wounds with orf virus IL-10 and VEGF-E dampens inflammation and promotes repair processes without accelerating closure,” will appear in an upcoming issue of Wound Repair and Regeneration.