Fall Laminitisi is Not Caused by Fructan

01/10/2026

Eleanor M. Kellon, VMD

I’ll get to the real causes in a minute, but the advice to graze in late afternoon would be a disaster if fructan was the cause because this is when fructan peaks.

I have been speaking out against fructan in forage being a cause of laminitis for at least 10 years. It’s not high fructan that causes problems, it’s high Ethanol Soluble Carbohydrates (ESC). They rise in tandem throughout the day and when nights are cool they stay high. The difference is that high ESC influences insulin but fructan does not.

A rise in Adrenocorticotropic Hormone (ACTH) which occurs in late summer and fall can trigger laminitis in uncontrolled PPID. Horses with Equine Metabolic Syndrome (EMS) may also be pushed over the edge by this seasonal hormonal shift even if they don’t have PPID. Be vigilant for changes in crest, other fat deposits, weight and activity. ACTH levels should be checked around mid-August to make sure the pergolide dose is adequate. By the time the seasonal rise is in full swing in late September, dosage increases are often less effective. These horses can, and do, develop laminitis with no access to pasture.

Grass fructan has never actually been proven to cause laminitis and the higher sugar levels in stressed grasses and fall regrowths, with the insulin spikes they cause, are the real reason. This is only an issue for EMS horses. This is not a matter of individual sensitivity to fructans. It is only the horses with EMS that are at risk.

EMS horses can also develop laminitis after free access to acorns. Very high intakes can cause poisoning in any horse but EMS horses develop laminitis with no other signs of toxicity because acorns are high in starch. It happens every year. Starch levels seem to vary from year to year and so does risk but don’t let that fool you into letting your guard down.

Another risk group is pregnant mares. Pregnant mares develop insulin resistance as pregnancy advances. This combined with increasing weight and pasture changes in the fall may result in laminitis. Mares managed to cycle and be bred early (January to March) are more at risk in the fall than those bred during the natural breeding season.

Management of at risk horses should include:

• prevent access to acorns
• make sure ACTH is controlled in PPID horses
• feed a suitably low sugar and starch diet
• limit (muzzle) or avoid pasture time when nights are below 40 F or there is obvious new green growth

It’s always important to supplement correctly to support healthy hooves. The horse can be assisted nutritionally by supplements which encourage the production of nitric oxide. Nitric oxide is a vessel dilating messenger that is the natural counterbalance to the vasoconstrictor endothelin-1.  The herb Gynostemma pentaphyllum (Jiaogulan) is a powerful support for nitric oxide. This is helped by providing the precursors for nitric oxide in the form of L-arginine and L-citrulline. Antioxidants also combat oxidative stress which inhibits the activity of the enzyme that produces nitric oxide inside blood vessels [eNOS – endothelial nitric oxide synthesis].

Magnesium and phosphorus are common deficiencies and important for energy generation and storage in metabolically active cells in the hoof. Selenium and iodine are common deficiencies also and both critical to normal functioning of the thyroid gland. Zinc, copper and biotin are often suboptimal and play important roles in normal hoof wall production and hoof integrity.

Proper management and supplementation can assist the horse in maintaining good blood delivery and avoiding nutritional roadblocks to normal hoof health and metabolism.

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About ECIR Group Inc. Started in 1999, the ECIR Group is the largest field-trial database for PPID and IR 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/IR 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 Insulin Resistance.

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.

Sources

1. Kagan I, Harlow BE, Flythe MD. A chromatographic method to monitor fructan catabolism in two cool-season grasses fermented by mixed bovine ruminal microbiota. Journal of the Science of Food and Agriculture Report. 2022. 2:264-271. https://doi.org/10.1002/jsf2.50.
2. Kellon EM. It’s Time to Put the Fructan Theory to Rest. https://drkhorsesense.wordpress.com/2015/06/22/its-time-to-put-the-fructan-theory-to-rest/
3. Kellon EM. The Seasonal ACTH Rise. https://drkhorsesense.wordpress.com/2019/08/04/the-seasonal-acth-rise/
4. Kellon EM. Use of the Herb Gynostemma Pentaphyllum and the Blue-green Algae Spirulina Platensis in Horses EEHNC - Congress - Ghent, 2006; European Equine Health and Nutrition Congress https://www.ivis.org/library/eehnc/eehnc-congress-ghent-2006/use-of-herb-gynostemma-pentaphyllum-and-blue-green-algae-spirulina-platensis-horses