By Heather Smith Thomas
The horse’s hock is one of the largest, strongest joints in his body, but often suffers injury and damage in a performance career. Good hind leg conformation and proper hock angle help—there’s not as much extra stress on any one part of the joint in a well conformed hock—but it is still difficult to keep hocks sound, with the use these horses are given. Some young horses also develop hock problems, even before they go into training.
Scott McClure, DVM (Iowa State University) says some horses develop juvenile spavin. “This may have to do with how mature the bones were when the horse was born,” he explains. The stress of weight bearing on immature bones may create damage and you might see bony changes at a young age.
“Conformation is a major factor in hock health, but another factor is use. No matter what we do when training young horses during their 2 and 3 year old years, there is a lot of repetitive stress and loading on those hocks. The lower 2 hock joints (the tarsometatarsal and distal intertarsal joints) are fairly immobile. They present most of the issues we have to deal with because they suffer the most concussion.”
Bone remodeling is a major issue. “We used to think in terms of cartilage problems, but new information from MRIs, CT scans, etc are showing that it may be as much remodeling of the subchondral bone plate, rather than the cartilage itself. The typical spavin in the lower hock—changes in the lower joint– is most common, though you can have other issues in the hock such as OCD, but those lesions are mostly at the top of the hock, at the tarsocrural joint. Most of those are usually correctable with surgery. You can remove an ODC lesion from the top joint,” he says.
“You can’t tell the owner to quit using the horse. Usually I tell them this is a manageable situation. When a horse starts showing hock pain, we start with some injections into those joints, to control the inflammation. With most horses, this is all we need to do for them to maintain soundness. After a period of time you may have to reinject the joints, but this may be all it takes to keep them going,” explains McClure.
“Corticosteriods injected into those lower joints will reduce the inflammation that is causing pain and the damage. If it’s a young horse in fairly heavy training, the inflammation will recur and require repetitive injections. Some horses need more intensive treatment. We can fuse those lower hock joints using a laser, or using ethyl alcohol,” he says.
Some trainers and owners try nutraceuticals that are promoted for aiding joint health. “In my opinion, most of those don’t have much value for the lower hock joints. Those joints don’t have a lot of motion or lubrication, so the nutraceuticals may not be that helpful in this situation. These are not something I’d use in a lower hock problem,” says McClure.
“In terms of cost effectiveness, direct injection of corticosteroids into the joint and the oral anti-inflammatories—such as bute, Banamine, and Firocoxib—are probably the most cost effective methods to treat hocks. Regarding the problems we deal with day in and day out, hocks are probably one of the most common things we treat. You just have to manage each horse individually on when they need to be injected again, or whether injections are going to work.”