From: Amanda
Dear Dr. Jahiel, I have a fairly broad question on cortisone injections in horses hocks. For the past two years every spring I have had these injections in my horse's hocks. I know the basics of this procedure, and I realize cortisone is a type of steroid that will strengthen the cartilage between the horse's bones. But I would like to receive more information on what actually happens on more of a sub microscopic level. Not only do I want to better inform myself of what is going on, but I am also seeking information for a High School term paper involved in Chemistry. I chose a topic that would interest me, and since I am very involved with horses and probably plan to base my future around them to a certain extent I chose cortisone injections in horses. I am hoping that you could tell me a little about what is happening here, and how the cortisone actually works to strengthen the hock. If this is too much information to request, then I completely understand. Thank you for your time! sincerely, Amanda
First, though, it's important to understand that cortisone does NOT strengthen the hock in any way. If anything, it weakens the hock. Far from strengthening the cartilage, cortisone injections DESTROY cartilage, and there is some evidence suggesting that it can also damage bone.
Cortisone is a steroidal anti-inflammatory, and it acts to reduce the inflammation and the pain that the horse experiences due to the arthritis in the hocks. This sounds as though it would be helpful, but it's not helpful to the horse. Pain and swelling are nature's way of saying "Slow down, don't put so much stress here, you're causing damage." When you reduce the pain and swelling, you keep the horse from getting that message - and so the horse does NOT take it easy, instead, it continues to work, and the damage continues to build. Cortisone is not a drug administered to a horse for the good of the horse; it's administered to horses because it's convenient for some human. Cortisone injections are very common amongst racehorses, for example - as far as the owners and trainers of those horses are concerned, the horses have one purpose only, and that is to run as fast as possible and win races. If injury or illness causes pain and swelling that would tend to slow a horse down, their "solution" is to use a cortisone injection to take away the pain and swelling so that the horse can race again. Cortisone is much less expensive than giving the horse time off, and since the horse is expendable, the idea is to "get a few more races out of the horse" before it breaks down completely.
Sad to say, this attitude has also permeated some competition barns, and instead of being given time out, horses are injected with steroids. The owner can then "get a few more shows out of the horse" before the end of the season.
You need to talk with your vet about the CURRENT condition of your horse's hocks.
If your horse is just beginning to experience arthritis in the hocks, ask your vet about products that can help stop the process of cartilage damage. There is some research that indicates that hyaluronic acid - if it's used early enough, before the cartilage begins to degenerate - may slow or even stop the process of cartilage damage.
If the process of cartilage degeneration is well under way, it's probably far too late to think in terms of improving or even salvaging cartilage. At this point, you're looking at quite another situation: the process of hock fusion has already begun, and if you want your horse to be sound in the long term, it will be to his advantage if you allow the bones of the hocks to fuse, without using anti-inflammatories to interfere with the process. It's not kind or realistic to think in terms of a long, active life AND regular cortisone injections. If you want to help your horse remain reasonably comfortable whilst his hocks fuse, talk to your vet about offering support for the symptoms. Heat can help with pain relief - neoprene hock boots are inexpensive, and your vet may have some other suggestions regarding non-invasive methods of dealing with local pain and inflammation.
A simple exercise program to help the process of fusion would involve long walks (with your horse either led, ponied, or under saddle) building up to several miles a day. Then you could incorporate trot-work, preferably in straight lines or very wide curves (not circles - which is also why longeing, unless you have a 60' "pasture longe line") isn't really practical.
Talk to your vet about how you can keep your horse moving, so that you can provide the horse with daily low-level exercise while causing minimum pain. Avoid using bute or steroids unless the vet feels that they are temporarily necessary on specific occasions when extreme inflammation is keeping your horse from moving enough to get that basic low-level exercise.
If you want your horse's hocks to fuse, the irritation that creates inflammation must be allowed to take place. It's difficult, I know - you want your horse to be comfortable, but in this case, making him comfortable in the short term isn't a useful goal. Instead, think of giving him the least amount of medication that will ease any severe pain and inflammation - not GET RID OF IT, but EASE it, that is, make it bearable, and make it possible for the horse to go on exercising.
When the process of fusion is complete, your horse shouldn't be in pain, but to get to that point, he will have to be in some pain for some time. Managing that pain when it becomes severe, and balancing the need for fusion and the need for exercise, is something that you and your vet need to do together.
In the meantime, here's what's happening inside those hocks. When the cartilage becomes thin and begins to wear away from the ends of the bones, and/or when the horse's joint fluid becomes thin or insufficient, the ends of the bones no longer slide smoothly over one another as they did when they were well-lubricated and coated with cartilage. The sliding of cartilage on cartilage during exercise and movement becomes a rubbing of bone on bone, and this causes irritation to the bone surface. That irritation signals the body to lay down calcium at the site, effectively building a layer of bone between the two edges of bone that rubbing against one another. When this calcium "bridge" is complete, there will be no more movement between those two bone surfaces - thus, no more rubbing, no more irritation, and no more pain and inflammation in surrounding tissues. If you've ever had a broken arm or leg, you've already had personal experience of the way in which the body builds a bone "bridge" between two pieces of bone.
When you're with your horse, you can't see what's going on inside its hocks, but you CAN sometimes feel heat in the hocks, or see swelling, and you can observe that the horse is in pain. Even if you are a good, conscientious owner who wants her horse to heal naturally and normally, even if you have NO intention of taking away the symptoms just so that you can ask the horse to run or jump, work on circles, or perform in a competition, you may be tempted to give your horse bute or ask your vet for additional cortisone injections, just to lessen the pain. The problem is that although the process of fusion IS painful, using anti-inflammatories on a regular basis will slow down or even stop the process - but won't heal the horse. By reducing or eliminating the body's natural inflammatory reaction, these drugs actually slow or stop the process of bone formation. Without the regular administration of anti-inflammatories, your horse will be in pain - but it will heal better and more quickly, because the bones of the hock will eventually fuse. WITH the regular administration of anti-inflammatories, your horse will be more comfortable in the short term, but healing will take much longer and may not take place at all. Meanwhile, the horse will have to deal with the side effects of the anti-inflammatories.
Cortisone as part of THERAPY is one thing, and it may be an appropriate component of therapy if the conditions warrant it, see below - but a conscientious vet will not use it exclusively, nor will he use it time after time, just as a conscientious doctor will not inject YOUR shoulder or elbow or knee time after time. The tradeoff isn't worth it - the horse (or you) will be getting temporary relief of symptoms, but that temporary relief comes at a high cost - that of dramatically accelerated permanent damage. There is some evidence that steroids may actually harm bone.
Arthritis is best attacked on all fronts at once - aside from the reduction of the rider's physical demands on the horse, joint nutraceuticals and hyaluronic acid injections may be all the treatment your horse needs if the problem is caught early enough. If your horse is suffering from extreme inflammation, and your vet's analysis of your horse's x-rays tells him that reducing that inflammation is a top priority, then he may opt to inject your horse's hocks with a combination of corticosteroids (e.g., cortisone) AND hyaluronic acid. These are the sort of injections that are often given to humans suffering from a major flareup of rheumatoid arthritis, and to some patients with osteoarthritis, with the goal of providing brief, temporary relief.
If you talk with your vet, or perhaps with another vet who is an equine specialist, you can find out more about this. To help you formulate your list of questions, you may also want to look through some back issues of "The Horse" and "Equus". This is a very common topic, and it's rare for any horse magazine to go more than a few months without an article on the subject.
Good luck with your Chemistry paper - I hope this gives you enough information to help your horse AND get you started with the assignment. You'll find the research interesting - but you'd better warn your teacher to expect a long paper! ;-)
Jessica
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