If you look at sensitive hoof tissues of a horse with septic laminitis and one with endocrinopathic laminitis under a microscope (called histology), you can tell the cases apart. Mechanical failure of the laminae, which suspend the coffin bone within the hoof, occurs in both, but it happens differently. In septic cases (with a toxic cause) inflammation and separation of the laminae are evident. In cases linked to endocrine problems, there’s stretching and increased cell proliferation, but no inflammation. These differences are helping scientists understand exactly how and why endocrinopathic laminitis occurs and in which horses.

Nicola Menzies-Gow, MA, VetMB, PhD, Dipl. ECEIM, Cert EM (internal medicine), MRCVS, senior lecturer in equine medicine at the Royal Veterinary College, in Hertfordshire, U.K., has devoted her research career to studying insulin resistance and equine laminitis. She described what scientists currently think happens in endocrinopathic laminitis cases—specifically those associated with EMS—and why during a series of laminitis presentations at the 2016 British Equine Veterinary Association Congress, held last fall in Birmingham, U.K.

The Horse-Human Metabolic Syndrome Conundrum

What researchers recognize as EMS has evolved slightly over the past 10-15 years; they now define it as a cluster of clinical and metabolic abnormalities that are associated with an increased risk of laminitis.

“It’s not these abnormalities equal laminitis, it’s an increased risk,” said Menzies-Gow. “And the (initial EMS) definition has come from human metabolic syndrome, I think that’s where we suffer a little bit when it comes to EMS. We’ve assumed because that if it happens in people like this, then it happens in horses like this, and that’s not always the case