Tendon injuries in the horse: current theories and therapies

Diagnosing, treating and preventing equine tendon injuries

source: Roger Smith and Michale Schramme
In Practice vol 25, no 9, October 2003
starts p 529, 9 pages long

Horses can sustain tendon injuries from external causes, involving bruises or wounds, or from internal causes, involving displacement or strain. Strain injuries are most common, and they mainly affect soft tissues supporting the horse's metacarpophalageal joint.

Most research on tendon injuries has been on injuries affecting thoroughbred racehorses, and nearly half of these have involved flexor tendon injuries, which appear to be more common when horse have to jump hurdles or fences than when they are flat racing. Older horses are more at risk. The superficial digital flexor tendon (SDFT) stores energy and provides elasticity. It degenerates as horses age, and can degenerate faster as a result of exercise. Fatigue, and carrying heavy weights, are among other factors that can make horses vulnerable to tendonitis. Horses can initially suffer from inflammation and lameness, which may persist if injuries recur due to exercise. Scarring can lead to loss of elasticity.

Diagnosis can initially be achieved through observation and palpating affected limbs, both in a raised position, and weightbearing. Diagnostic ultrasound can help in discovering the severity of injuries.

Treatment depends on the phase of the episode, with the initial aim of reducing inflammation. Rest, cold hydrotherapy, gentle physical therapy that is under the pain threshold of the horse, anti-inflammatory drugs, polysulphated glycosaminoglycans, and a surgical treatment called tendon splitting, have all been found to be useful. The aim of treatment in the next phase, fibroplastic or subacute, is to improve scar tissue quality. Walking exercise can be combined with utltrasound monitoring, with exercise reduced if it appears to be hampering healing. Drug therapies, such as use of growth factors, may also help. Horses vary according to how fast they recover. Premature canter work can lead to setbacks, and ultrasound is helpful is assessing how much exercise to give the horse.

Preventing tendonitis is important, since healing tends to involve tissue repair, not regeneration. A number of factors can help, including appropriate training regimes and assessing risk factors, such as the weight carried by the horse, the ground surface, and the horse's level of fatigue. The article examines diagnosis, training and prevention of tendonitis in greater detail.