Florida researchers have confirmed that some Arabian horses have a genetic predisposition for developing equine metabolic syndrome (EMS), obesity and, in turn, laminitis, a painful and often devastating inflammatory condition of the hoof.
Horse owners and veterinarians have long observed that certain breeds and bloodlines seem to be more susceptible to EMS and associated laminitis. Looking for evidence to confirm these suspicions, researchers at the University of Florida collected genetic information from 64 Arabians, half with a history of metabolic-related laminitis and half without.
Samantha Brooks, PhD, explains that the focus on Arabians came after preliminary research suggested that the breed is at risk for high insulin levels, an important characteristic of EMS. “In a preliminary study, we examined the frequency of abnormal insulin levels across breeds,” she says. “We found the obvious answers---yes, ponies were more frequently found to have high insulin levels---but also some unexpected ones. Arabians were nearly as frequently affected with high insulin as were Morgans and gaited breeds.”
When analyzing genetic data from the two groups of Arabians, the researchers discovered that those with a history of laminitis carried particular genetic markers near a gene identified as FAM174A. Perhaps the most significant was a marker shown by previous research to be associated with elevated insulin values and obesity.
Although not much is known about the FAM174A gene, Brooks says, the information currently available supports the idea that it may be related to EMS. “This is not a well-documented gene,” she says, adding that after the first part of the study was done with 64 horses, her team retested their hypothesis with an additional 50 horses---114 horses total. “One report suggests it is important for cholesterol homeostasis. If alterations in its expression change cholesterol homeostasis in the EMS-prone horse, then that could represent a new potential avenue for intervention and therapeutics.”
Even before that is possible, though, knowing the location of the gene can pave the way for genetic testing to determine a horse’s laminitis risk so that precautions can be taken.
“Armed with the knowledge that you have an individual horse at higher-than-average risk, you are prepared to take preventative action through changes in management,” says Brooks. “[Testing] could also be used to reduce risk in future foals through selective breeding.”
Reference: “Genomewide association study reveals a risk locus for equine metabolic syndrome in the Arabian horse,” Journal of Animal Science, March 2017
This article first appeared in the December 2017 issue of EQUUS (Volume #483)