Think insulin resistance is just for ponies that are fat?

Don’t think that.

Now scientists know that the breed’s where it’s at.

Previously, scientists believed easy keepers—horses and ponies that gain and keep weight easily—metabolized insulin differently than their slim herdmates because of their increased body fat. But British and Australian researchers have determined that metabolic differences from one breed to another are present even in equids that aren’t fat.

“By comparing nonobese animals in moderate body condition, we have found that there are underlying fundamental differences in insulin responses between horse types as well as between horses and ponies,” said Simon Bailey, BVMS, PhD, FHEA, Dipl. ECVPT, MRCVS, associate professor in preclinical veterinary sciences at the Faculty of Veterinary Science at the University of Melbourne, in Australia.

This means certain breeds—such as Andalusians and ponies, which were used in the study along with several other breeds including Morgans, Tennessee Walkers, Paso Finos, and possibly some Quarter Horses—are more prone to developing problems related to excessive insulin production, partly because of their genetic makeup, Bailey said.

Insulin resistance in humans can lead to diabetes; in horses it is associated with equine metabolic syndrome (EMS). The high insulin levels resulting from EMS can increase a horse's risk of developing the hoof disease laminitis, said Bailey. Insulin normally helps clear glucose from the bloodstream; however, Bailey said, insulin resistance causes the horse or pony to produce more