There are literally hundreds of oral joint supplements on the market for horses. If you look at a horse magazine, it seems about half of the ads are for joint supplements and all claim to be the best. Marketing of these products is crazy, and they all have testimonials from successful horse folks and theories about why your horse has to have their product. In reality, only a few of these products are actually backed by scientific studies supporting their claims, and scientific studies have proven that about only 10% of these products actually contain the ingredients they list on the label.
You may be wondering how this is possible because aren't all products required to be tested? Unfortunately, they are not, and these oral joint supplements are listed as feed supplements instead of drugs so the FDA does not regulate them. And then the other question is do these oral joint supplements really work as the advertisements say they do? To answer this question, researchers at the University of Utrecht tested the effectiveness of one oral joint supplement to see if it improved gait stiffness in older horses over a three-month period. The researchers took 24 older horses and divided them into two groups. Only one group was given the supplement. The supplement contained glucosamine, chondroitin and MSM. Results indicated there was no significant improvement is stride length, knee flexion, fetlock extension, or hock range of motion. This does not mean that all of the joint supplements do not help horses. It does indicate, however, that it is best to ask the manufacturer for scientific proof rather than relying on testimonials.