Conditions or ailments that are the cause of a problem that you see - your observation.

Your vet may diagnose

Extensor Tenosynovitis, Non-Infectious

Synonyms: Extensor Tendon Sheath Inflammation


The extensor tendon sheaths are balloon-like spaces enclosed by a thin membrane and containing a small amount of synovial fluid (egg yolk-consistency fluid that provides lubrication and nutrition to the tendon). These tendon sheaths are located on the fronts and sides of the highest motion areas in the limb; the carpus in the forelimb and the hock in the hind limb.

Direct trauma to the extensor tendon sheaths causes local swelling over the face of the carpus or hock, usually without much lameness. This is probably most common in jumping horses that hit a jump. There are several tendon sheaths over the face of both the carpus and hock. The particular pattern and location of swelling will depend on which tendon sheath is injured.

In some cases, injury to the tendon itself within the sheath also causes chronic swelling. Fortunately, in most cases these injuries are considered only blemishes. They usually do not cause lameness or reduction in performance.

Veterinary diagnosis requires examination and ultrasound. In some cases, the tendon sheath fluid needs to be sampled.

Treatment depends on the severity of tendon injury and mostly revolves around quieting the inflammation within the space, often with injection of various anti-inflammatory drugs.

my vet's role


Good, although swelling may persist and result in slight thickening of the area even long term. It can be difficult to completely eliminate swelling.

my role

Questions To Ask Your Vet:
  • Does this injury cause lameness or reduce performance, or is it just a blemish?

Select horses of good conformation for your intended purpose or discipline.

Conditioning: Tendons strengthen with conditioning and gradually increasing load. Always over-condition your horse for the work asked of him. Long, slow, distance work-such as a 30- to 45-minute walk/ trot -is ideal, as this strengthens tendons and ligaments without stressing them. Ensure overall fitness exceeds work level and expectations.

Good footing. Uneven or deep footing causes tendon and ligament injury. Never ride a horse in bad footing (too deep or too thin or hard).

Hoof care:Maintain excellent hoof balance and short shoeing or trimming interval to prevent hoof overgrowth and excessive torque on ligaments and tendons of lower limb.

Warm-up: Plan to walk a horse under saddle a minimum of 10 to 15 minutes before you start to work.

Recognize subtle signs of lameness before they become severe. Notice swelling, heat or digital pulse in your horse's limbs by learning what constitutes normal (WHE). Observe your horse's limbs before you ride and take note of any changes you notice.

further reading & resources

Author: Doug Thal DVM Dipl. ABVP