Ask The Vet: Nutrition

Courtesy of AAEP

Question: I would like to give my 15-year-old trail horse gelding a joint supplement to help prevent joint damage. I have read that Condroitin and MSM are not absorbed from the horse’s gut. I have also read that oral HA should be given as a liquid, and might even do harm if given dry because of it’s adsorption properties. What should a preventative joint supplement contain? Do you think a periodic IM or IV product might be a better choice than an oral product?

Answer: Thanks for giving me a great opportunity to set the record straight on some commonly held misconceptions! First, I’m not sure where you read that about the absorption of Chondroitin and MSM. An excellent study showed that low molecular weight Chondroitin Sulfate had a 32% absorption rate in the horse while high molecular weight had a 22% absorption rate (1). This is much lower than the 70% absorption rate seen in humans and dogs, but proof that the ingredient has bioavailability in the horse.

Second, regarding MSM, Pratt and others presented a paper at the 17th Equine Science Society meeting called “A study of the absorption of methylsulfonylmethane in horses” that used MSM with radio-labeled sulfur and demonstrated an absorption rate of 55% (2). There are a number of other studies that show the benefits of MSM specifically in horses, to the musculoskeletal system (especially joints), the respiratory system, and the skin.

Third, I have not heard that about hyaluronic acid (HA). The most-quoted study of HA in the horse did use a gel to administer the ingredient orally (3), but that doesn’t mean that all HA has to be given in a liquid form.

As far as what a joint supplement should contain, there are lots of choices out there! For a teenage horse like yours, being lightly ridden, I would suggest glucosamine, chondroitin sulfate and MSM at a minimum. At this age there is likely to be some wear and tear from a lifetime of work, so depending on his soundness and comfort level, you may want to consider additional ingredients like the HA you mention, ASU (avocado soybean unsaponifiables), omega 3 fatty acids, cetylated fatty acids, and others.

Finally, an eight-year study demonstrated that consistent use of an oral glucosamine/chondroitin supplement resulted in a decreased need for distal tarsal joint injections to maintain soundness in a group of show hunters/jumpers. I firmly believe that the combination of oral supplements and injectable medications (whether directly into the joint or systemically, that is, into the muscle or vein) results in the healthiest joint tissues. I hope this information and the research studies below answered some of your questions!

1. Biopharm Drug Dispos. 2004 Apr;25(3):109-16. The bioavailability and pharmacokinetics of glucosamine hydrochloride and chondroitin sulfate after oral and intravenous single dose administration in the horse. Du J, White N, Eddington ND.

2. Proc 17th Equine Nutr Physiol Soc:141-2. A study of the absorption of methylsulfonylmethane in horses. Pratt SE, Clarke AF, Riddolls L, McKee S.

3. Equine Vet J. 2006 Jul;38(4):375-8. Oral hyaluronan gel reduces post operative tarsocrural effusion in the yearling Thoroughbred. Bergin BJ, Pierce SW, Bramlage LR, Stromberg A.

4. Intern J Appl Res Vet Med. Vol. 4, No. 2, 2006. Effects of Oral Glucosamine and Chondroitin Sulfates Supplementation on Frequency of Intra-articular Therapy of the Horse Tarsus. Martha R. Rodgers, VMD.

Question: How can I determine if my horses are getting the proper daily nutrients? Where can I find the nutrients they should get along with the minimum and maximum? I can calculate what they get, I just don’t know if it is enough, too much, etc.

Answer: The National Research Council (NRC) published the sixth revised edition of Nutrient Requirements of Horses in 2007. It’s considered the “bible” of horse nutrition and I recommend consulting this book to help you figure out how much of which nutrients your horses require. Some versions of the book include software to help you calculate your horse’s needs, which you may find helpful.

As much as I love math and nutrition though, I’m perfectly happy letting the experts in this field tell me what to feed my horses because it’s easy to make a mistake and cause serious consequences. My job as a horse owner is just to provide 2% of their body weight per day in high quality forage (which I have analyzed so I know its nutrient composition), then bridge any gaps with a ration balancer or multi-vitamin/mineral supplement. In addition, I add salt to my horse’s diet (since forages and grains are both low in sodium), provide plenty of fresh water and that’s it! Follow these guidelines and your horses will have everything they need.