Back in 2003, a class of drug that has found wide use in the human medical field was introduced into the equine world. The class of drugs are called bisphosphonates, and the generic name of the drug used in horses is tiludronate. You’ve probably heard of it – it goes by the trade name of Tildren.® And, in the years since its introduction, the horse world – especially the performance horse world – has subsequently gone a bit mad.
Bone is an active tissue. New bone is constantly being made and removed (that’s one reason that you can break your arm and it can heal). In normal bone metabolism, the formation and removal of bone gone hand-in-hand. It’s because bone is an active tissue that bisphosphonate drugs can have an effect.
Not all bisphosphonates are equal, however. Tiludronate is one of the older members of this group of drugs. Frankly, it doesn’t work nearly as well as do newer drugs. In fact, it is as much as 10,000 times less effective than the drugs that are currently used in people. Not only doesn’t it work as well, tiludronate is also less safe than are newer members of the bisphosphonate group. And that’s probably why, in humans, it’s not prescribed anymore. In fact, the company that made the tiludronate for humans, Sanofi, took if off the human market in the US in 2012.
- First, the conditions for which the drugs are used in humans pretty much don’t exist in horses.
- Second, just about nobody in veterinary medicine has any expertise with this class of drugs.
SECOND ASIDE: I think that a lot of the popularity with Tildren® was a result of a phenomenon known as “The Allure of the Foreign.” It’s been going on for centuries. Otherwise stated, if you can’t get something easily where you are, you must need it, and it must be good. This curious phenomenon is seen in clothing, in investments, in tennis teachers. It’s why some people find foreign accents so attractive. Tildren® had to be obtained in the US by special import license, so it had to be good, right?
Basically, all of a sudden there was this new therapy, and it was supposed to do something to bone, and lots of people latched onto what I think was a pretty simplistic equation of how the drugs worked:
Problem involves bone + problem might cause some bone loss + drug may stop some bone loss = BETTER!!
Amazingly, all of this simple math was done without much knowledge of what was actually happening at the level of the horse’s bone. And, honestly, we still don’t know. Which is a bit unsettling, because, fundamentally, you’d think that it would be a good idea to know what a drug really does before you started running into horses. At least I would.
Some of the things for which Tildren® are being used are just silly. For example, on the show circuit, the drug is apaprently being used as some sort of bone “maintenance.” The idea – I guess – is that by by trying to stop bone from being removed by the osteoclasts, you end up with more bone, or stronger bone, or something. But that’s just silly. That’s not how bone works. For bone to be healthy, there has to have a balance of production and removal. If you skew the balance, bad things can happen, and, in people, where they use potent bisphosphonate drugs for real conditions, bad things (side effects) do happen.
Here’s the bottom line. If you are giving your horse Tildren® you’re basically enrolling your horse in an experiment where no one is keeping track of the results. You’re using an old, fairly ineffective medication to treat conditions for which the drugs aren’t used in the species (human) where the class of drugs is most commonly used. If you’re using it as some sort of “maintenance” therapy, you’re going out on a limb which isn’t attached to a tree. You’re using an expensive, unapproved medication based on the idea that your horse’s problem probably involves the bone, and that the drug probably does something to bone. And that may be OK with you – but I think that at least you should know.
Medicine doesn’t progress nearly as fast as our hopes for it, and our hopes often outpace common sense. So it goes.
* The origin of this phrase is British, probably Cockney. The Oxford English Dictionary references an 1846 Punch magazine cartoon entitled ”The Ministerial Crisis.” The weekly humor and satire magazine has a cartoon or showman telling a customer, ”Which ever you please, my little dear. You pays your money, and you takes your choice.” And here’s the cartoon, too!