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

Your vet may diagnose

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.

my vet's role


Generally good. Although these swellings may be difficult to treat, in most cases, treatment is unnecessary as the swellings are cosmetic only.

If swellings are connected to the joints, then treatment of the joints may be beneficial.

my role


I might observe

You might make these observations when a horse has this condition.

Very Common
Less Common
more observations

Questions To Ask Your Vet:

Stall door banging behavior can cause hygroma or ganglion. If necessary, change management or use protective bandaging to protect this area.

Chronic arthritis can lead to synovial hernia. Treating early signs of arthritis can reduce hernia formation.

Author: Doug Thal DVM Dipl. ABVP