“Digital flexor tendon and suspensory ligament injuries are very common in horses, but horses can also suffer from ligament injuries inside the joint, such as collateral ligament, cruciate ligament, and meniscal ligament injuries. These ligament injuries within the joint can cause joint instability, post-traumatic osteoarthritis (PTOA), and persistent pain in horses, where joint replacement is not an option,” said Lauren Schnabel, DVM, PhD, Dipl. ACVS, ACVSMR, professor of equine orthopedic surgery at North Carolina State University, in Raleigh, during her presentation at the inaugural American College of Veterinary Sports Medicine and Rehabilitation Symposium, held April 27-29 in Charleston, South Carolina.

Using Orthobiologics to Preserve Equine Soundness

In lieu of joint replacements, veterinarians can use orthobiologics to minimize the chronic effects of tendon and ligament injuries in horses. Veterinarians commonly use adult mesenchymal stem cells (MSCs) in animals, and researchers are studying their positive effects on tissue repair in human clinical trials.

“To date, the greatest evidence for the use of bone-marrow-derived MSCs (in horses) is in the treatment of superficial digital flexor tendon injuries, where it has been shown that MSCs can reduce the rate of reinjury by helping to heal the tendon with more normal elastic tissue instead of scar tissue,” said Schnabel. “There is also increasing evidence for the use of MSCs to treat meniscal injuries and other ligament injuries within the joint. We know that the goal is to treat early to help prevent PTOA, but we are still studying the best times to treat and how often, what to deliver them with, and how to deliver them.”

Veterinarians use blood-generated orthobiologics such as platelet-rich plasma (PRP), autologous conditioned serum (ACS), and autologous conditioned plasma for the growth factors and anti-inflammatory cytokines they contain. However, products vary considerably depending on the individual horse and the preparation process, added Schnabel. “The horse’s systemic health, hydration status, whether they have been fasted or not, whether they have been exercised or not, and any non-steroidal anti-inflammatories or sedatives in their system can all affect these products.”

Some platelet products, such as platelet lysates, are pooled from multiple donor horses and used for their antimicrobial peptides, growth factors, and anti-inflammatory cytokines to fight infection and heal tissue. Amnion-derived (from the embryo membrane) products, which veterinarians also collect from donor horses, are proving useful for multiple applications, she said, including tendon and ligament healing and modulating the immune system. “With any donor product, there has to be stringent quality control and sterilization processes in addition to screening of the donors for transmissible diseases,” said Schnabel.

Take-Home Message

Veterinarians have several regenerative therapy options at their disposal when treating horses with tendon and ligament injuries. The product they choose typically varies based on the severity of the injury, the horse’s age, and owner goals for the horse’s career. When used in conjunction with other therapies and a rehabilitation plan, orthobiologics might increase the likelihood of a favorable outcome.