A Comparison Study of Hyaluronan (HA) and Polysulfated Glycosaminoglycan (PSGAG) and their Effect on Equine Sport Performance

Holly Stewart

Mentor: Dr. Tina Leuthard
Pioneer Equine Veternairy Service
Alamo, CA

In many different kinds of English-discipline riding, the value of a horse is assessed on its movement. A desirable horse is one that moves freely forward opening its stride and having what is referred to as “fluid joints.” What this term references is the ability of scope of the horse’s movement. In reality, there are very few horses that truly have this ideal kind of movement and can sustain the necessary level of flexibility and extension required for sports performance for a long period of time, thus leading horse owners, riders, and trainers to look toward other, artificial options.

Oral supplements that have high levels of glucosamine are becoming increasingly popular because of their availability and relatively inexpensive price. In addition to oral supplements, there are a number of prescription glucosamine injections that can be administered. For my research project I chose to investigate the two most competitive injectable glucosamine supplements on the market: Adequan and Legend. Both of these products make very similar claims, but have a very different chemical make-up and approach to lubricating the joints. My goal was to try and assess which product had an overall better effect on horses.

I started with a group of 12 horses: 2 control horses, 4 horses on Adequan (2 of which were introduced to Adequan during the study, 2 that were continuing to use Adequan), 4 horses on Legend (2 of which were introduced to Legend during the study, 2 that were continuing to use Legend) and 2 horses on both Adequan and Legend. I took blood panels of all of the horses to gain a good starting ground. Over the next 8 weeks I followed the conditioning, diet and competition schedules of these horses and followed their performance. I also ran more blood panels, conducted interviews and ran a number of physical flexibility tests.

My results were somewhat inconclusive. I found that some horses seemed to really be affected by being on the glucosamine, while others showed little or no change. There were minor changes in the blood work of the horses in the study, but no noticeable trends. Much of the gathered information ended up being somewhat subjective, which made it difficult to draw any solid conclusions. This research is ongoing however. I am continuing to look at these horses over a longer period of time, running further blood tests, running a series of radiograph tests (to try and observe concrete physical changes), and expanding my study group of horses.

Glucosamine products in equine sports performance is a lucrative industry where further research needs to be done to fully understand their effectiveness. Joint degenerative conditions continue to be a significant limiting factor for horses in a variety of kinds of activities and work.


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