Veterinarians can often predict where a horse might be sore, based just on the horse's athletic endeavors. Jumping, for instance, is hard on the coffin joints. Roping and driving can be tough on the withers and shoulders. But there's one ailment that seems to be prevalent in just about every equine endeavor: hock pain. That makes hock problems a subject that we all should understand, especially learning what we can do to free our horses of performance limiting problems arising in the hocks. Download a PDF of this article here.
SEVERAL JOINT SPACES IN ONE.
The hock joint is a rather unique joint. Midway down the hind leg, it makes up the articular junction between the tibia and the cannon bones. it's actually made up of several rows of bones, each its own joint pouch. So, in a way, there are several joint spaces in the hock. Interestingly, three of the four joint spaces hardly bend at all (which more or less negates what it means to be a joint!). They simply are rows of bones stacked on top of one another.
But don't let this fool you. Just because they move minimally doesn't mean that they can't develop bone spurs and pain. Oddly enough, the top space (called the tibiotarsal or tarsocrural space) that does all of the bending, shows signs of degenerative change less often than the lower less-bending spaces. Yes, you read it right: The joint space that bends seems to be OK much of the time, whereas the spaces that aren't flexing much seem to show all the wear and tear!
So, where is this wear and tear coming from? Commonly, the joint spaces that make up the hock will become inflamed due to the repetitive trauma brought on by activity. Joint inflammation (arthritis) erodes cartilage and results in bone spur production in these spaces. See signs of hock pain sidebar.
PREDISPOSING FACTORS. We've established that repetitive trauma on the joint from athletic performance can cause degenerative changes to the cartilage and bones. But, why do some horses seem to suffer more from hock arthritis than others? There are several possible reasons:
1) Some types of riding are more likely to lead to hock problems than others. Race horses and futurity Quarter Horses that train heavily in the juvenile stage of their lives often show early signs of hock-related pain. Jumping horses and reiners commonly have hock issues. Even though You'll still see plenty of hock-sore horses in other disciplines, it seems that some are just more likely to cause problems than others.
2) Genetics likely play a role in arthritic degeneration of joints. Sometimes there's little to explain why a horse has hock problems. For instance, a horse that has been given ample time to "grow up" and has been given access to pasture to roam may still show arthritic changes early in life.
Some horses that are worked very hard (like 5,000-mile endurance Arabians) will have beautiful hock joints when radiographed, while other horses that have been worked very lightly (such as a warmblood doing training-level dressage) may have some scary bone spurs.
Can it be that they just have "bad hocks" running in their blood? Likely yes, since there are hundreds of documented instances in which young, lightly used horses show severe degenerative hock joint changes for no explicable reason other than "being born that way."
3) Swinging on the genetic coat-tails is osteochondrosis aka OC or OCD. Known to have a genetic component, this defect in the cartilage lining the joint spaces can lead to premature arthritis. Although it most commonly occurs in the stifle, the hock comes in close second as the joint of predilection. OC is also linked to diet and accelerated growth in foals. Although a relatively few horses are affected by osteochondrosis, it definitely should be counted as a predisposing factor to hock pain.
4) Management can play a large role in the exacerbation of hock pain. The saying, "Bodies in motion tend to stay in motion" really rings true with horses too. Their joints can stiffen up at a relatively young age if they're forced to stand still in a stall day in and day out.
Think about it: If you take a 16-hand horse and stand it in a 12x12 stall for 22 hours per day that would be similar to you going into your coat closet and spending most of your time there. We don't give these horses much room to move! If we stood still for two hours, most of us would complain of some pain. Since their nervous systems work the same as ours, and their joints are made up of the same components as ours, it's only plausible that they suffer from the same dolorous sensations that we do when they stand still all day in s stall.
5) Conformation. See hock conformation sidebar.
ADDRESSING HOCK PAIN. Simply identifying hock pain is half the battle for veterinarians, as some horse owners practically require an intervention in order to get them to admit that their horse has hock problems. But once you can prove that to yourself, you're well on your way to a happier horse.
We've covered subjects such as cortisone, joint supplements, joint health, and physical therapy options in depth in past articles. All of that information applies to hocks. Here we'll discuss the most successful methods for managing painful hocks. See hot or cold therapy sidebar.
1) Joint supplements: Adequan, Legend, Pentosan, glucosamine, chondroitin, and MSMare among the dozens of supplements that can aid aching joints. These products must be given in adequate dosages to make a difference, so be sure you read the product label before you purchase it to ensure it can get the job done. Read about Adequan vs. Legend vs. Pentosan.
2) Management changes such as weight loss and turn-out can make a tremendous positive difference in combating hock pain. it's no secret that excess pounds weigh heavy on the joints, and that horses standing in box stalls have stiffer joints than those who live out in large open spaces.
3) Topical application of DMSO (generic), Surpass (requires prescription from your veterinarian), arnica liniment (we suggest Sore No-More) or capsaicin (we like Capsa-Cream) or the use of hot/cold therapy (see sidebar) can also alleviate joint pain.
4) NSAIDs. Daily feeding of non-steroidal anti-inflammatory (NSAID) medications is common with hock issues. However, we know this practice can lead to gastro-intestinal disturbances. If you must rely on NSAIDS, using Previcox (yes it's made for dogs, but you can use it with horses - ask your vet) or Equioxx (both firicoxib) may be a safer choice since these products tend to be gentler on the stomach and colon than bute, banamine, aspirin, ketoprofen or naproxen. Talk with your veterinarian.
5) Cortisone injections. Injecting the hock joint spaces with cortisone is an excellent way to provide long term anti-inflammatory effect and pain relief in the hock joint. Depending on management factors such as weight, stabling and the horse's activity (discipline and intensity), an owner may see a duration of action that lasts between six and 15 months following hock cortisone injections. The long-term benefit of cortisone makes this option popular among horse owners managing hock pain.
6) Tildren or zoledronic acid administration can help to strengthen the cortices of the hock bones by increasing their calcium content. Owners who have had limited success with other therapies have reported that the administration of these medications has helped their horses with hock issues.
7) In extreme cases, surgical drilling of the hock joints or chemical fusion of the hocks via joint injection has been able to stabilize painful horses. In most of these cases, performance will still be limited and the horse may still experience some pain, but hock fusion can provide some pain alleviation in a subset of cases.
BOTTOM LINE. Horses often experience hock pain relatively early on in life, so simply identifying horses with hock pain is a huge step toward solving the problem. Hock-joint conformation variations can either aid or hinder a horse depending on the type and level of your riding.
Hock joints tend to respond well to many types of therapies, so if you're looking to address a hock issue, call your veterinarian now. There are many options for horses with sore hocks.
Article by Contributing Veterinary Editor Grant Miller, VMD.