One of the more popular products used in an effort to prevent or treat horse joint disease is called Legend®. Made by Bayer Pharmaceuticals, Legend® is a brand of hyaluronan (it was always called hyaluronic acid before, and for the purposes of typing, let’s call is HA). It’s injected into the horse’s jugular vein, and it’s supposed to have all sorts of wonderful benefits for the horse’s joints. Of course, just about everyone is concerned about their horse’s joints,
and the appeal of a product that can be injected intravenously, and that will then go everywhere, and benefit every joint, is as undeniable psychologically as it is implausible medically.
The implausibility of IV HA is a big problem. Basically, it doesn’t make any sense that it should work. After IV HA administration, HA’s time in the body is extremely short. After 3 hours, what’s been given IV can’t be detected. Furthermore, the body is always making HA anyway, and the body’s own production of HA is 1 – 4 times the recommended IV dose. So, basically, it is pretty hard to understand how giving such a relatively small dose of a substance, that lasts such a short amount of time, could make a clinical difference in an animal that is producing the substance continually, and producing it in greater amounts than that which is administered “therapeutically.”
The problem with giving HA IV in hopes of getting a therapeutic effect is the same concept as carrying on a conversation at a loud concert and hoping to significantly increase the noise. There’s so much noise going on at the concert anyway that no one is going to pay attention to one more conversation. In that same vein (pun intended), there’s little reason to think that giving a little bit of a substance that’s always in the bloodstream – and at higher concentrations – will make any difference at all to the horse’s body that is receiving it.
From a scientific standpoint, there is a little bit of support for the product. The product was approved, which means it was tested, and one study in a small number of horses, and one in a few dogs, showed some changes in a few of the things that were measured (although the majority of the things that were measured didn’t show any changes). In fact, given the buckets of Legend that are given to horses – in hopes of somehow “helping” their joints – it’s really surprising that there’s so little research into it. And, as far as humans go – where you’d think that the big market for such a product might be – there’s no research at all. With such a huge potential market – humans with joint problems – if the product were effective in other species, one might reasonably wonder why the most lucrative market of all isn’t being mined.
The bottom line is that I think that the plausibility problems make it extremely unlikely the “Legend” can be effective. I certainly don’t consider it a first choice – or even a second or third choice – in treating horses that have existing joint problems. And as far as “preventing” joint problems, that’s just a big can of worms because there’s no way to predict if an individual horse will ever develop them.
Otherwise stated, if you give your horse something to prevent a problem, and the problem doesn’t happen, does that mean that the product “worked?” If so, I’ve got some rhinoceros repellent to sell you… if you use it, I can pretty much guarantee that your horse won’t get chased by a rhino (guarantee does not apply to some parts of Africa and India).
The only real direct harm from “Legend” will come to your pocketbook. It’s certainly safe, so you don’t have to worry about hurting your horse if you use it. And, if you’re willing to pony up the cash for it, and you feel better for having given it to your horse, that’s fine. But if you’re looking for a product that’s likely to have some important therapeutic effect on your horse’s joints, it’s probably best to look elsewhere.
