Horse Side Vet Guide ®

Equine Health Resource

Carpal Hygroma, Synovial Hernia, Ganglion

The equine carpus (knee) is a complicated region, with 3 joints and several tendon sheaths.

Hygroma, synovial hernia and ganglion are similar kinds of fluid filled swellings over the front of the carpus. In most cases they are all thought to be caused by direct trauma to the area.

A synovial hernia (a/k/a blown knee) is an outpocketing of the inner soft joint capsule that pops through a defect or tear in the fibrous joint capsule surrounding the joint.

A ganglion is an isolated fluid filled structure near a joint.

A hygroma is also a fluid filled capsule surrounded by tissue.

Each of these problems has a different treatment plan and prognosis. These swellings are usually only cosmetic and are not associated with lameness because they usually do not involve the knee (carpal joints) themselves.

A synovial hernia can be seen with chronic arthritis. Any swellings in this area can restrict range of motion of the carpus, which usually does not affect the horse.

In a veterinary exam, these swellings are differentiated from joint swelling and extensor tendon sheath swellings, which also appear as fluidy swellings in the same area.

Author: Doug Thal DVM Dipl. ABVP


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