Fused hocks in horses.

Have you heard of fused hocks in horses? These can either develop at a young age (juvenile osteochondral disease, as shown in the second x-ray image below), through degenerative joint disease, or sometimes through other trauma. Fused hocks tend to occur in the distal intertarsal and tarsometatarsal joints (the lower two joints in the hock). These joints have relatively low mobility.

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A normal hock – note the space in the centre of the joint (the middle black line) compared to the image below.

How long does it take for hocks to fuse?

The process of bones fusing together is called ankylosis; in the hocks, the duration that this takes to complete can vary drastically between each individual horse.

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A fused hock – note the lack of space (no black line) in the centre of the joint.

Are fused hocks painful?

It is assumed that fused hocks are less painful, however the full fusion is a very slow progress. If hocks are not entirely fused, they have the potential to cause discomfort. Medication of the joints may enable the horse to continue to move without pain whilst the process is underway, however this should be monitored by the vet, including the use of diagnostic imaging, to determine progress. Once the hocks are fused, any discomfort or lameness tends to be eliminated, and the horse should usually be able to carry on in normal work.

There are some surgical options to fuse hocks, but they have to be considered very carefully.