Discoveries in Equine Metabolic Syndrome

New light is being shed on this syndrome which often affects middle-aged obese horses and certain breeds.
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New light is being shed on this syndrome which often affects middle-aged obese horses and certain breeds.
Middle-aged obese horses and certain breeds can be prone to equine metabolic syndrome. | © Arnd Bronkhorst

Middle-aged obese horses and certain breeds can be prone to equine metabolic syndrome. | © Arnd Bronkhorst

Equine metabolic syndrome, a disease associated with a disorder of the endocrine system, often develops in middle-aged obese horses. It’s become a growing problem in the horse population, yet many questions remain unanswered. 

Simply defining the disease is a challenge because it can present in various ways, including through a collection of health issues, such as excess fat deposits, insulin resistance and a predisposition to laminitis. The disease may be genetically linked, and certain breeds—including Morgans, Arabians, Paso Finos and pony breeds—may be more prone than others. EMS is also linked to Cushing’s disease, another common endocrine disorder that affects older horses, as both can cause laminitis. A hormonal test is the best way to differentiate between the two. 

Interestingly, EMS is similar to human metabolic syndrome, which has been linked to changes in the microbial makeup in the intestines. This led researchers from the Gluck Equine Research Center at the University of Kentucky and the University of Guelph in Ontario to develop a study comparing the fecal microbial makeup in horses with EMS to metabolically healthy horses. (Fecal microbiota is the bacterial population found in your horse’s manure. It’s used as a rough approximation for the bacterial population in the horse’s intestines.)

The team, including Sarah Elzinga, J. Scott Weese and Amanda Adams, studied 10 horses with EMS and 10 healthy control horses. The EMS horses were identified through blood-testing to determine insulin resistance. In addition, researchers assessed body condition (including levels of body fat), cresty-neck score and history of or predisposition to laminitis. 

Fecal samples were collected from all 20 horses. Researchers then conducted DNA analysis of the samples to discover what bacteria were present and in what proportions. Researchers found that the EMS horses had less diversity in the types of microbes in their intestines than the control horses. 

“These results shed further light onto what it means to be a horse with EMS,” said Elzinga. “In particular, it indicates that the gut is highly involved in this syndrome and is important to consider when designing research, feeding and caring for these horses.” —Sushil Wenholz

This article originally appeared in the September 2016 issue of Practical Horseman.