What causes a horses leg to swell?

Answer 1

The short answer is increased fluid in the leg causes swelling. However, this doesn't necessarily help you address the issue, as the increased fluid in the leg can be due to multiple causes.

One of the big causes of swollen legs in horses is injury, including bowed tendons and other soft tissue injuries. The treatment for a minor soft tissue injury is rest, mild compression with leg wraps, and more rest. If the injury is severe, your horse may need surgery to put the tissues back together again.

Another big cause, particularly in horses that are travelling long distances in trailers, is called "stocking up". This is the accumulation of edema fluid in the legs caused by inadequate activity; most trainers will have their horses' legs wrapped for travel before loading to help prevent this. However, once your horse gets out of the trailer and can walk around getting his circulation moving again, the edema will resolve on its own.

Answer 2

Leg swelling can be caused by multiple things. Firstly would be what is called 'Stocking up' where the horse has been out working and is then stalled. Lymph fluids, blood and other bodily fluids can build up in the legs through lack of movement. Another fairly common reason is a systemic infection in the horse. Either way you should call a equine veterinarian out to have a look at the horses legs. This will help to rule out illnesses and to give proper care instructions for the leg swelling.