Myths and Misconceptions about Equine Metabolic Syndrome 

Eleanor M. Kellon, VMD

It always takes a while for textbooks, veterinary schools, and practitioners to catch up with the best published research.

Magazines and news feeds often focus on whomever has a better and louder PR network. There are also companies and individuals that seek to capitalize on owners’ concerns, offering products or services that may even claim to be science-based but are not. The end result is a lot of advice that at best is not helpful, and at worst is harmful. These are a few of the latter.

Short chain (or any length) fructans cause insulin to rise. This is sometimes presented as a need to look at starch plus water soluble carbohydrates (WSC), which includes some fructans, versus hydrolyzble carbohydrates (HC) of starch plus the simple sugar only, ethanol soluble carbohydrates (ESC), when evaluating the safety of a hay or other food item. This misunderstanding can cause people to reject perfectly safe hay and waste time and money looking for hay that ends up being overly mature and nutritionally inferior in many ways, such as digestibility, protein and vitamin/mineral levels. Look for ESC + starch less than 10%, and don’t worry about fructan unless NSC [WSC + starch] is over 40%.

Insulin resistance is an inflammatory condition. Metabolic syndrome in humans is associated with elevation of a number of inflammatory proteins called cytokines but the picture in equines is far less clear. Suagee, et al., 2012 found no correlation between insulin levels and inflammatory cytokines like TNF-alpha and IL-6 that are elevated in IR humans. Vick, et al., 2007 found a correlation between IR and TNF-alpha levels but only in mares older than 20. No other cytokine changes. Burns, et al., 2010 found higher inflammatory cytokine levels in the neck crest fat but no difference between normal and IR horses. Laminitis in IR horses is also not inflammatory. This is important because it explains why the response to NSAID drugs for pain in IR horses is typically poor and why these drugs do not “treat” anything.

Whole foods” can prevent/cure metabolic syndrome. It’s not too clear where this idea came from, but I suspect it is referring back to the difference between how things like white bread versus whole grain products produce higher glucose and insulin spikes in humans. That’s true, and it’s also true that processed (e.g., extruded) barley and corn are more digestible to glucose in horses. However, that does not mean that whole oats or whole corn will be safe. They most definitely are not. It also does not mean that heat-processed grains or co-product foods like brans or wheat midds cause EMS. Food does not cause metabolic syndrome and many of these co-products are lower in sugar/starch and higher fiber than the whole food.

XYZ supplement or feed will make it safe for your metabolic syndrome horse to return to pasture. All the evidence points to IR being an inherent part of the horse’s metabolic makeup. They are born this way. When food is scarce and of poor quality, IR is actually a survival advantage–but not for domesticated horses. Nothing can change the way the horse was born. Proper management will keep it from being a health issue but free access to grass is rarely possible for them. Grass is a living tissue and its levels of sugar and starch will vary. Things like type of grass, weather conditions, stage of growth, severity of IR, and level of exercise influence how safe (or not) some degree of grazing may be but no supplement will make it safe for you to just turn an IR horse out on grass. You may get away with it for a while but sooner or later there will be problems.

Glyphosate (Round Up) causes metabolic syndrome. All herbicides are potentially toxic but like all things potentially toxic there will be a dangerous level (dosage matters) and also predictable effects that are discovered in the course of toxicity studies. Glyphosate has been blamed for just about any human medical condition you can think of. More recently, claims focused on horses, including that glyphosate causes EMS. The proposed mechanism for this is glyphosate substituting for the amino acid glycine in cellular insulin receptors. Problem is, this is 100% speculation with zero evidence to show this happens and at least one formal study, Antoniou, et al., 2019, shows it does not. The people making these claims have a “Dr.” before their name by virtue of a PhD but their area of expertise has nothing to do with physiology, biochemistry, medicine, toxicology, or nutrition. Would you go to your dentist for advice on a hysterectomy or to your gynecologist for a hip replacement? Don’t take advice about food choices from a computer scientist. There are often benefits to organic foods but going non-GMO won’t eliminate equine metabolic syndrome.

If you want to read an excellent, up-to-date, scientific article on laminitis and insulin resistance written by researchers who actually work in the field, go to: .

For more information go to


Suagee JK, Corl BA, Crisman MV, Pleasant RS, Thatcher CD, Geor RJ. Relationships between Body Condition Score and Plasma

Inflammatory Cytokines, Insulin, and Lipids in a Mixed Population of Light-Breed Horses. Dec 2012, J Vet Int Med.

Vick MM, Adams AA, Murphy BA, Sessions DR, Horohov DW, Cook RF, B. J. Shelton BJ, Fitzgerald BP. Relationships among inflammatory cytokines, obesity, and insulin sensitivity in the horse. JAnim Sci 2007.

Burns TA, Geor RJ, Mudge MC, McCutcheon LJ, Hinchcliff KW, Belknap JK. Proinflammatory cytokine and chemokine gene expression

profiles in subcutaneous and visceral adipose tissue depots of insulin-resistant and insulin-sensitive light breed horses. J Vet Intern

Med. 2010 Jul-Aug;24(4):932-9.

Kellon EM, Inflammation in Equine Metabolic Syndrome (EMS), ECIR Group Inc., 2017 NO Laminitis! Conference, Tucson, AZ, USA,

Antoniou MN, Nicolas A,  Mesnage R, Biserni M, Rao FV, Martin CV. Glyphosate does not substitute for glycine in proteins of actively dividing mammalian cells. BMC Research Notes volume 12, Article number: 494 (2019).

Patterson-Kane JC, Karikoski NP, McGowan CM. Paradigm shifts in understanding equine laminitis. The Veterinary Journal, Volume 231, January 2018.

About ECIR Group Inc.
Started in 1999, the ECIR Group is the largest field-trial database for PPID and EMS in the world and provides the latest research, diagnosis, and treatment information, in addition to dietary recommendations for horses with these conditions. Even universities do not and cannot compile and follow long term as many in-depth case histories of PPID/EMS  horses as the ECIR Group.

In 2013 the Equine Cushing’s and Insulin Resistance Group Inc., an Arizona nonprofit corporation, was approved as a 501(c)3 public charity. Tax-deductible contributions and grants support ongoing research, education, and awareness of Equine Cushing’s Disease/PPID and EMS.

THE MISSION of the ECIR Group Inc. is to improve the welfare of equines with metabolic disorders via a unique interface between basic research and real-life clinical experience. Prevention of laminitis is the ultimate goal. The ECIR Group serves the scientific community, practicing clinicians, and owners by focusing on investigations most likely to quickly, immediately, and significantly benefit the welfare of the horse.

Contact:  Nancy Collins

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