Lacerations, burns, chronic nonhealing wounds, cast sores, and other skin-related ailments affecting the lower limb pose treatment challenges for even the most experienced veterinarians. The decreased blood flow and dearth of soft tissue to help mend horse wounds in this area contribute to prolonged healing, poor aesthetics, and even excessive granulation tissue (aka proud flesh).
As such, practitioners are always on the hunt for new treatment options to help improve wound healing outcomes. At the 2017 American Association of Equine Practitioners Convention, held Nov. 17-21, in San Antonio, Texas, Annette M. McCoy, DVM, MS, PhD, Dipl. ACVS, described how veterinarians can improve wound healing using a product that might seem more at home in the neonatal wing of a clinic: amnion.
“Equine amnion, the relatively thick innermost layer of the fetal tissues, contains numerous biological molecules that promote tissue growth and wound healing,” said McCoy, an assistant professor of equine surgery at the University of Illinois College of Veterinary Medicine, in Urbana. “Examples include epidermal growth factor, transforming growth factor-β, and vascular endothelial growth factor. In addition, amnion recruits stem cells to wound beds to facilitate healing.”
Commercial equine amnion products are available as either a shelf-stable sheet or a liquid; however, McCoy said, during foaling season, fresh amnion is readily available to many practitioners and can be processed (ideally within an hour of foaling) and stored for later use.
“One placenta can easily produce dozens of dressings that cost approximately $1 each, which is far less expensive than commercial dressings,” she said. “Considering that many of these cases require long-term care, the cost differential between homemade amnion and commercial dressings can be impressive.”
She described two techniques veterinarians can use to successfully harvest and store amnion, along with the pros and cons of each; the techniques are detailed in the conference proceedings. Both protocols can be performed with minimal setup, relatively quickly, and with no specialized equipment, she noted.
McCoy said veterinarians can apply amnion to the skin and allow it to desiccate (dry out). However, she said she prefers to place the amnion directly on the wound and under a bandage that’s changed every three to seven days, depending on the case.
“We have found equine amnion to be a valuable addition to our toolkit for managing horse wounds healing by second intention,” she said, referring to those wounds whose edges cannot be sutured and, so, must heal by adhesion of granulating surfaces. “The protocols described here are easy to use and readily adaptable to a wide range of practice situations.”