Treatment of Equine Tendon Injuries

Tendon injuries are a diagnosis every equine owner dreads. Here’s what to do to ensure the best outcome in the event your horse injures a tendon.

It was two days after the 4th of July when I decided to take my horse Milagro for a ride alone on the trail. We live in an equestrian community with well-groomed bridle paths, and I planned to have him out for about an hour. We were only about half a block from home when it happened.

I heard a car coming down the street we had just turned off. One minute I heard the motor, and the next minute, a loud pop. Someone had thrown a firecracker out of the car window in our direction.

Milagro is solid on the trail—he’s my North American Trail Ride Conference (NATRC) competitive trail horse—but firecrackers are his nemesis. He bolted in terror, racing up the trail at a mad gallop, away from the sound.

In an effort to stop him, I turned his head and pushed him with my leg into a tight circle. But the bridle path that once seemed wide and safe was not big enough for a terrified, runaway horse.

As I turned him, his back hoof landed on the sloped driveway of one of the homes adjacent to the trail. I felt his back end going down. He scrambled and got his feet under him, but not before he let out a horrible scream.

I jumped off and examined his back legs. I didn’t see anything obvious, even as I led him home. His adrenaline was racing, and he was practically dragging me.

An hour later in his paddock, he had calmed down. It was then that I noticed he was dragging his left hind toe. I called out the vet, who examined him by lifting the affected leg and stretching it out behind him. Instead of bending at the hock, the leg extended straight out in a way that turned my stomach.

“He’s got a rupture of the peroneus tertius tendon,” my veterinarian said.

How Tendon Injuries Happen

Tendon injuries can occur in two ways: through chronic overuse, or through trauma. Because horses’ legs are made up of a number of tendons, they are prone to stress and injury.

“Tendon injuries result from sudden tears or ruptures from a single overloading event, or chronic strains from overuse,” says Annette McCoy, DVM, M.S., Ph.D., Dipl. ACVS, associate professor of Equine Surgery at the University of Illinois College of Veterinary Medicine.

“The former are usually recognized right away after an athletic episode, and usually have the hallmarks of heat, focal pain when touched, and obvious swelling,” she explains. “The latter can result in low-grade chronic lameness that can be difficult to diagnose.”

The most commonly injured tendons and collateral ligaments that support joint stability in non-racing horses are the suspensory ligament, deep digital flexor tendon, the check ligament and the superficial digital flexor tendon, according to Jennifer G. Barrett, DVM, Ph.D., DACVS-LA, DACVSMR-EQ, Theodora Ayer Randolph professor of Equine Surgery at Marion duPont Scott Equine Medical Center at the Virginia Maryland College of Veterinary Medicine.

Varied Treatment of Tendon Injuries

The way a tendon injury is handled right after it’s discovered can make a big difference in the ultimate outcome.

“Right after an injury happens, we are trying to combat inflammation and swelling,” says McCoy. “This is accomplished with a combination of cold therapy like icing or cold-hosing, compression with bandaging, systemic medications like a non-steroidal anti-inflammatory drug [NSAID] such as phenylbutazone [bute], and stall rest.”

Although scarring of the tendon as it heals cannot be prevented, making the scar tissue as functional as possible is the goal.

“Controlled exercise in a rehabilitation program helps us to do that,” says McCoy. “Periodic re-evaluation with ultrasound helps us determine the healing progress. A rehab program might need to be altered, depending on how the tendon is healing.”

A number of adjunct therapies can also be used to help tendons heal, including extracorporeal shock-wave therapy, therapeutic ultrasound, and low-level laser and magnetic therapy, although not all of these therapies have been studied in clinical research.

“Biological therapies such as platelet rich plasma [PRP], autologous conditioned serum, and mesenchymal stem cells injected directly into a tendon injury under ultrasound guidance have shown some promise at either speeding healing, improving the quality of the healed tissue, or helping to reduce the incidence of re-injury,” says McCoy.

“More work is needed to understand exactly how these treatments work, and what injuries are best addressed by using them,” she adds. “This is a very active area of ongoing research.”

There are some tendon and ligament injuries that can benefit from surgical treatment, according to Barrett.

“Examples include the suspensory ligament in hind limbs, the deep digital flexor tendon, and superficial digital flexor tendon when they are injured in a tendon sheath or bursa,” she says.

Slow Recovery

When a horse injures a tendon, the issue can require a temporary layup or permanent retirement.

“Prognosis is entirely dependent on the severity and location of the injury, but typically ranges from fair to guarded for future athletic use,” says McCoy. “An owner should expect that their horse will be out of full work for nine to 12 months while the injury heals. Unfortunately, horses that have had a tendon injury are highly prone to re-injury.”

The way the layup and rehabilitation are handled can make a huge difference in whether the horse is able to return to his previous activity.

“The hardest thing for owners to understand is that healing takes a very long time for tendons and ligaments,” says Barrett. “Humans can rest by taking the weight off the limb completely. This is not possible for horses, so we rely on reducing exercise as much as possible during healing.”

Stall rest is the best we can do to limit trotting and overuse of a healing tendon, but stall rest is hard for owners, and is often seen as hard for horses too, according to Barrett.

“The same way you need to be on crutches to heal a tendon, horses need stall rest and very controlled exercise once your veterinarian determines it appropriate,” she says. “All of the difficult and expensive care your veterinarian provides [might] be wasted if the exercise recommendations are not followed.”

The length of stall rest and the limited exercise needed to help the horse recover depends on the injury. Extensive stall rest is usually prescribed early in recovery, with a gradual return to gentle exercise as the tendon heals.

“Early loading—exercise—of the tissue is the most essential aspect of healing, but we can’t load too much, otherwise it breaks again,” says Henk Offereins, DVM, of equinetendon.com, an Ireland-based equine management service specializing in the area of tendon injuries. “Getting that balance right [is the difference between] success and failure in rehabilitation.”

Update on Milagro

Milagro made a full recovery after rupturing his peroneus tertius tendon, but only after a one-year layup that required three straight months of stall rest with physical therapy on the affected leg. He eventually graduated to hand-walking, slowly building up the amount of time he could be walked over a period of months.

Today, he is back to trail riding around our community as well as competing in NATRC events. He is so sound these days, I often forget he ever suffered this horrible injury. I believe the long layup and following my veterinarian’s instructions on rehabilitation made all the difference.

Key Takeaway

Tendon injuries are as complicated as equine injuries come—and certainly time-consuming to recover from. Understanding treatment options and the recovery timeframe can help horse owners and caretakers to better manage any future tendon injuries.

Further Reading:
◆ Managing Horses with Tendon and Ligament Issues
◆ Taking Care of Your Horse’s Tendons

This article about equine tendon injuries appeared in the April 2024 issue of Horse Illustrated magazine. Click here to subscribe!