The Horse:Your Guide To Equine Health Care provides monthly equine health care information to horse owners, breeders, veterinarians, barn/farm managers, trainer/riding instructors, and others involved in the hands-on care of the horse.
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A53 TheHorse.com/AAEP2017 March 2018 THE HORSE AAEP Wrap-Up YOUR GUIDE TO THE 2017 AAEP CONVENTION SPONSORED BY STACEY OKE, DVM, MSC Procuring, Preparing, and Applying Amnion for Equine Wound Healing L acerations, burns, chronic nonheal- ing wounds, cast sores, and other skin-related ailments of the lower limb pose treatment challenges. The de- creased blood flow and dearth of soft tis- sue to help mend these wounds contribute to prolonged healing, poor aesthetics, and excessive granulation tissue (proud flesh). So, vets are always on the hunt for treatments. Annette M. McCoy, DVM, MS, PhD, Dipl. ACVS, described how they 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 profes- sor of equine surgery at the University of Illinois College of Veterinary Medicine, in Urbana. "Examples include epider- mal growth factor, transforming growth factor-ß, 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; but, she said, during foaling season, fresh amnion is readily available and can be processed (ideally within an hour of foaling) and stored for later use. "One placenta can easily produce doz- ens of dressings that cost approximately $1 each, which is far less expensive than commercial dressings," she said. "Con- sidering that many of these cases require long-term care, the cost differential be- tween homemade amnion and commer- cial dressings can be impressive." She described two processing tech- niques vets can use, along with the pros and cons of each. Both protocols can be performed quickly, with minimal setup and no specialized equipment, she noted. McCoy said vets can apply amnion to the skin and allow it to desiccate (dry out). However, she prefers to place the amnion directly on the wound, under a bandage that's changed every three to seven days. "We have found equine amnion to be a valuable addition to our toolkit for man- aging wounds healing by second inten- tion," she said, referring to those wounds whose edges cannot be sutured and, so, must heal by adhesion of granulating surfaces. She said the protocols for prepa- ration are easy to use and readily adapt- able to a wide range of practice situations. Manuka Honey and Healing Time It can take a frustrating amount of time and energy to treat some horse wounds— especially those in challenging locations. Vets and owners alike are often willing to try an array of salves, sprays, and dress- ings to facilitate a positive outcome. But a researcher recently reminded practitio- ners to reach for a particular product, one that created some "buzz" a few years ago: Honey, particularly manuka honey, can also help wound healing. "This type of honey has antibacte- rial and immunomodulatory effects, and recent studies support the use of manuka honey on wound healing in the equine distal (lower) limb—a notoriously challenging location to treat effectively and economically," said Albert Tsang, BVSc (Hons.), a research student at the University of Sydney School of Veterinary Science, in New South Wales, Australia. Whether different types of manuka honey help heal wounds similarly and if a certain "special" ingredient exists in manuka honey and not in commer- cial honey remain to be determined. To help answer these questions, Tsang and colleagues created full-thickness skin wounds (2.5 cm 2 ) on eight horses' cannon bones. and treated them with manuka honey, multifloral ("generic") honey, or a saline control. They found that wounds treated with manuka honey healed faster than those treated with generic honey or saline. Healing times were 90.78, 100.3, and 101.36 days, respectively. "It is possible that processing using heat of generic honey may have inacti- vated some of the biologically active mol- ecules in honey that contribute to wound healing," he said. Tsang also noted that the clinical effects on healing naturally occurring wounds caused by trauma and contaminated (as wounds occurring in the field often are) might be even better than those observed in his study. The reason remains unclear. The researchers' next step involves iso- lating manuka honey's bioactive constitu- ents with the goal of further improving equine wound healing. h COURTESY DR. ANNETTE MCCOY Two Ways to Heal Wounds DAY 1 DAY 12 DAY 60 The progression of healing from Day 1 to 60 of amnion treatment.