Tendon Lesions in Horses: Treatment and Prognosis
If an owner finds his or her horse in the field, a foreleg covered in blood from the knee down, the animal's tendons might not be the first concern. But as Robert L. Linford, DVM, PhD, Dipl. ACVS, a professor in the Department of Clinical Sciences at the Mississippi State University College of Veterinary Medicine, explained at a recent veterinary conference, even the tiniest leg laceration can have dire consequences for nearby tendons if left untreated.
At the 2012 Western Veterinary Conference, held Feb. 19-23 in Las Vegas, Nev., Linford discussed the clinical signs associated with certain tendon lacerations, along with the treatment options and prognoses, during a presentation for a veterinary audience.
Where Are the Tendons?
"Tendon lacerations are serious injuries for horses because a seemingly simple wound may cause a crippling lameness," Linford explained. "Any laceration below the elbow or stifle has the potential to sever a major tendon."
The first step in understanding tendon injuries is to know, generally speaking, where some specific structures are positioned within the horse's lower legs:
Linford said that often times diagnosing a tendon disruption isn't overly difficult. Some disruptions tend to cause characteristic signs, which he described:
Once a veterinarian diagnoses the type of tendon injury, he or she can make recommendations for treatment and determine prognosis.
Prognosis, Treatment, and Recovery
Linford explained that without appropriate treatment, tendon injuries often don't heal properly, "leading to a loss of biomechanical function of the limb and, ultimately, a crippling injury." He reviewed a few general studies that looked at the treatment type and/or prognosis for specific tendon injuries:
Veterinarians treat most tendon injuries using broad-spectrum antibiotics and some type of surgery, Linford said. Some of these surgical procedures--such as for partial tendon tears with no synovial involvement or for extensor tendon lacerations--can be performed in the standing, sedated horse, he said. More complex procedures--such as those for completely lacerated flexor tendons--should be performed under general anesthesia, he noted.
In some cases, Linford noted, a tendon or ligament injury can involve a joint (or synovial structure). While early studies found these horses had a 2.5-fold greater chance of euthanasia, a more recent study showed that synovial involvement has little to no effect on patient survival when prompt, aggressive, appropriate treatment can be done. In the event a joint is involved in a tendon disruption, Linford recommended starting the horse on broad-spectrum antibiotics and lavaging (flushing) the affected joint to reduce the risk of sepsis development. He suggested debriding and closing wounds involving synovial structures, although he noted that veterinarians should not close "heavily contaminated and severely traumatized wounds" until healthy tissue has developed at the wound margins.
Linford reviewed the steps in surgically repairing lacerated tendons with the veterinary audience. Post-surgery the horse's affected leg needs to remain immobilized and the animal will require stall rest, but exact treatment protocol depends on the injury's severity.
Complete extensor and partial flexor tendon lacerations typically require four to six weeks of stall rest with the tendon immobilized in a Robert Jones bandage (a layered and padded bandage designed to limit limb mobility). Stall rest should be followed by 10 to 12 weeks of controlled exercise and a subsequent increase in turnout and gradual return to work, Linford said.
For complete flexor tendon lacerations, Linford suggested the horse be stabled with the limb immobilized in a flexion splint or a cast for six weeks. Following splint or cast removal, he recommended supporting the fetlock in a support sling shoe for 10 to 12 weeks. "Unrestricted turnout and free exercise are not recommended in the six to eight months following surgery," he cautioned. Mature, well-organized scar tissue should be visible on ultrasound and the horse should be sound for six weeks prior to turnout and free-exercise, he stressed. Linford recommended keeping the horse out of athletic training for 10 to 12 months following surgery to allow any completely severed tendon to fully heal.
A veterinarian should be closely involved with rehabilitating every horse after a tendon injury. He or she will prescribe stall rest, controlled exercise, free-choice exercise, and eventual return to work as each individual patient dictates.
No horse health procedure is without risk, however. Linford noted that common complications resulting from tendon injuries and subsequent treatment include pain from adhesions, joint disease, tendon sheath adhesions, annular ligament constriction, reinjury, and repair failure.
Although a lacerated or severed tendon is a nightmare for most horse owners, Linford relayed that veterinary technology now allows for many such injuries to be repaired successfully. Understand the risks and that not every horse will recover fully, but also know that working closely with a veterinarian can help an affected animal return to soundness and his intended use.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.
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