In this ongoing series, I look at supplements for horses and any studies that are done on efficacy.
Go into any tack, feed or other horse-supply store, and you will find a wide variety of supplements that will help your horse do anything from move better, gain weight, grow a healthier coat to just be a better horse.
My question is: Do any of them work?
How do you know if a supplement works? Supplements are expensive and there is little scientific evidence that any of them do what their label claims.
Smartpak posted a blog on joint supplements and responded to a question of whether they are absorbed and if they are effective. This blog had four citations to studies that “prove” the effectiveness of these supplements. The study it cites to show that the joint supplements are absorbed seemed to be a reasonable methodology for testing the claim, but with only 10 horses in the study, this is preliminary evidence at best. Granted, for the horse studies I’ve seen, 10 is an average number. However, for any study to be statistically applied to the entire population, assuming a homogeneous population of horses (which may be a stretch), the sample size ought to be greater than 30.
The article goes on to talk about how effective joint supplements are for horses. I was unable to find information on the first citation about methylsulfonylmethane (MSM), so I cannot comment on the quality of this study.
The next citation is about how Hyaluronan (HA) is absorbed orally. This study was done well. It had a placebo ground (which many studies lack) and a decent-sized group of 27 joints in the treatment group. This study specifically looked at orally administered HA on horses’ joints after surgery. It compared how swollen the joints were in the groups of horses and found that HA helped reduce the swelling. The question here: How does this apply to a healthy horse? These were also yearling horses, so can this be applicable to older horses? I’m not saying these studies are not useful. I’m saying we need a lot more research before we put every horse on these supplements.
The final study cited is not much more than a case study. A trainer had 10 horses which were being given hock injections of HA. The horses were studied for two years, then a glucosamine and chondroitin supplement was added to their diets twice daily for eight years. This study found that those horses “needed” fewer injections of HA during those eight years. The person conducting the study was also responsible for giving the injections, so there was no blinding of the study. Also, no placebo group was used. Quite a bit of bias could happen in a study such as this, which is why a placebo group is needed.
Were these really the best studies to prove the points in this article? If so, we as an equine community have a long way to go before we will know if all of these supplements actually are helping our horses.
This study reflects the state of research on joint supplements on horses. We can only draw viable conclusions if we hold our studies to rigorous scientific standards – which I believe we should.
I’m not saying that you should stop supplementing your horses. You should be aware, though, that the supplements may not have any benefit for your horse and you may just be wasting your money. I am advocating more research, held to a high standard, and honesty with buyers of supplements.