Key Updates for Diagnosing Equine Metabolic Syndrome

Equine metabolic syndrome (EMS) affects a large population of idle, leisure, and sport horses, putting them at risk of developing laminitis. Diagnosing EMS can be challenging, which may delay treatment. To facilitate the diagnostic process, the Equine Endocrinology Group (EEG) created comprehensive guidelines that describe available tests and their interpretations, and lead to various management options.^*

“EMS is best addressed through veterinary and client education pertaining to diagnosing disease and implementing appropriate feed and management practices,” explained Catherine Whitehouse, M.S., a nutrition advisor for Kentucky Equine Research.

The EEG’s guidelines were recently updated and are available online.^* According to the group’s coordinator, Nicholas Frank, D.V.M., Ph.D., from the Cummings School of Veterinary Medicine at Tufts University, the key updates in the 2022 Guidelines include the following:

• Offering more information on measuring insulin concentrations when horses have recently eaten to assess how an individual horse is responding to those feedstuffs.
• Providing guidance in using stall-side insulin and analyzers.
• Clarifying the use of the insulin tolerance test. This is a dynamic test that involves administering insulin intravenously to measure the effect on insulin sensitivity.
• Introducing the glycemic pellet challenge rather than or in addition to the standard oral glucose test.
• Feeding straw as part of a nutritional management plan.
• Discussing the concept of thresholds for laminitis with respect to insulin concentrations.

To better understand these updates, veterinarians are encouraged to review the guidelines. Owners can then discuss with their veterinarians what test would be best.

“The newly updated guidelines also introduce SGLT2 inhibitors as a new class of drugs for treating EMS,” Whitehouse said.  These drugs block the kidneys from resorbing sugar from the urine. As a result, less sugar circulates in the horse’s bloodstream, and this may decrease insulin levels. Abnormal insulin levels, or insulin dysregulation, is a key feature of EMS.

Like the earlier version of the guidelines, the 2022 version focuses heavily on dietary management of EMS.

Horses diagnosed with EMS are often overweight, although that is not always the case.

“Weight management is essential in many EMS horses, which often requires strict feeding programs. Forage and feeds should be provided by weight rather than volume, and the calorie content of these feedstuffs should be carefully reviewed,” Whitehouse said. “Pasture access may need to be prohibited or managed in such a way that intake levels are restricted. Even when restrictive measures are in place, grazing can be troublesome for certain horses.”

Forage-based diets need to be fortified with vitamins and minerals for optimal health.

“Owners should consider diets low in nonstructural carbohydrates, such as forage-based diets coupled with a low-intake ration balancer or a concentrated micronutrient supplement to deliver these essential nutrients,” advised Whitehouse.

^*Frank, N., S. Bailey, F.-R. Bertin, T. Burns, M. de Laat, A. Durham, J. Kritchevsky, and N. Menzies-Gow. 2022. Equine Endocrinology Group. Recommendations for the diagnosis and management of equine metabolic syndrome.