Tendon injuries in horses can signal the end of an equine’s athletic career, although there are many horses that successfully return to riding, and competition, albeit sometimes at a lower level, after appropriate treatment and a significant recovery period.
In order to understand why and how these injuries occur, it is helpful to be familiar with the structures involved.
Tendons are the straps of connective tissues that attach a muscle to other body parts, usually bones. They transfer the force of muscle contraction to the bones enabling movement; the tendon is firmly connected to muscle fibres at one end and to components of the bone at the other end.
While tendon injuries are a common problem in horses, tendons are actually remarkably strong, with relatively high tensile strengths for a soft tissue. Their great strength is due to the impressive anatomical structure and tissue composition of the tendon fibres. They contain many collagen fibres running in parallel orientations.
The tendons in the horse’s lower leg include:
- the extensor tendon at the front of the leg
- the superficial digital flexor tendon at the back of the leg
- the deep digital flexor tendon located at the back of the leg between the cannon bone and suspensory ligament, and the superficial digital flexor tendon
Causes of tendon injuries
A damaged tendon occurs when the tendon is strained, which is when the fibres within the tendons in the lower leg are overloaded (internal damage) or when they suffer an impact injury (external damage). Typically the individual tendon fibres are broken, similar to an old rope fraying. When this happens there is a large inflammatory response with swelling around the injury and the horse is likely to be lame.