Like keeping the pistons of an engine lubricated for smooth, easy movement, the tendon sheaths of a horse function similarly by providing a friction-free environment in which tendons can move. But if the lubricant becomes fouled, engine malfunction follows. It’s the same with a horse’s tendons. That can mean big-time problems: Neither the four-wheeled or four-legged vehicle will run without serious repair!

Tendons run down the front and back of a horse’s lower limb. Clinical signs of septic tenosynovitis include swelling of the limb and tendon sheath due to excess fluid, heat, pain on palpation, and lameness. | Dr. Robin Peterson Illustration

The tendon sheath is a fluid-filled sleeve that envelops and lubricates the tendon and provides an environment in which the tendon can smoothly move and change direction where there is joint movement. But if sheath-penetrating injury occurs, infection can follow. Even a simple wound can become septic, putting the horse at risk for permanent lameness and even death.

Septic Insights

Septic tenosynovitis, or a septic tendon sheath, describes an infection that produces inflammation in a tendon sheath. Usually caused by a puncture, laceration, or trauma, septic tenosynovitis most often occurs in the digital tendon sheath (behind the fetlock) and the tarsal sheath (behind the hock), as these are the