ems in arabians
Nature vs. nurture. It’s a topic that’s been at the center of debate not only in the field of psychology but also when it comes to conditions such as equine metabolic syndrome (EMS). Do horses develop it due to genetics (nature) or management practices (nurture)?

A research team from the University of Florida and Cornell University say both play an important role in EMS development. But they’ve recently carried out a genomewide study that’s allowed them to link a specific gene to EMS. If this gene is identified early enough, they say, it could help prevent this commonly diagnosed condition that has potentially deadly effects.

“Our preliminary work seemed to confirm horseman’s lore that some breeds of horse were clearly more susceptible to EMS,” said Samantha Brooks, PhD, assistant professor of equine physiology at the University of Florida, in Gainesville.

The researchers recruited 64 Arabian horses (Population 1) that, due to suspected EMS, had recently undergone diagnostic testing of fasting plasma insulin and adrenocorticotropic hormone (ACTH) levels at Cornell University’s College of Veterinary Medicine Animal Health Diagnostic Center endocrinology laboratory. Horse owners voluntarily submitted a brief medical history, body measurements, pedigree, photos, and hair or blood samples for their horses.

The team also collected blood samples from 50 Arabians from a Florida farm (Population 2). Many of the horses in this population were considered obese, but only one had previously been diagnosed with laminitis.

In Population 1, they identified markers on Equus caballus chromosome 3 that are near a gene—FAM174A—that appeared to be linked with EMS. The team also found that these markers correlated with elevated circulating insulin levels, triglycerides (fats), body condition score, and laminitis—traits associated with EMS diagnosis.

Then, the researchers genotyped horses from Population 2 in addition to 102 previously banked hair samples from horses of five different breeds (Population 3) to determine the FAM174A gene’s frequency in horses from varying ancestries.

The genomewide study revealed that specific regions on FAM174A correlated with elevated circulating insulin levels, triglycerides (fats), body condition score, and laminitis—traits associated with an EMS diagnosis.

“To date, this is the first genetic locus for EMS to be identified and validated in the horse,” the researchers said.

Brooks said this type of genotyping is fairly simple and could be commercially available very soon.

“Horses carrying the risk-associated genotype could be monitored more closely from birth and put on preventive diets,” she said. “Our work suggests that there may some potential treatments that focus more on regulating lipids, rather than sugars. Once these are investigated we can hope that owners will have more effective options for managing their horses.”

The study, “Genomewide association study reveals a risk locus for equine metabolic syndrome in the Arabian Horse,” was published in Journal of Animal Science.