Diet and the insulin response in metabolic horses under scrutiny

“Understanding How Diet Composition Influences Insulin Response in Horses with Equine Metabolic Syndrome,” is a one-year study by Amanda Adams from the University of Kentucky's Gluck Equine Research Center.
File image. Image by Daron Herbert from Pixabay

A study on how diet influences insulin response in horses with Equine Metabolic Syndrome is among more than a dozen research projects involving horses to have received part of nearly $US1 million in grants from the Morris Animal Foundation.

“Understanding How Diet Composition Influences Insulin Response in Horses with Equine Metabolic Syndrome,” is a one-year, $47,570 study by Amanda Adams, PhD, associate professor and Mars Equestrian Fellow at the University of Kentucky’s Gluck Equine Research Center.

Adams and her team will study how diet composition affects insulin levels in horses with equine metabolic syndrome as a step toward improving dietary recommendations to control this condition.

Equine metabolic syndrome (EMS) is a growing problem in horses. The disease is a leading cause of laminitis, a painful and devastating inflammatory condition of the hoof. Insulin dysregulation (ID), a condition where insulin levels fluctuate abnormally in response to feeding, is a component of EMS. There is a lack of informative studies on the nutritional management of ID and EMS. Researchers plan to analyze data on EMS horses fed five different forage diets to better understand insulin response. This new information will be used to help improve dietary management of EMS-ID horses.

Other equine research by various institutions includes work on heart arrhythmias, the gut microbiome, eye cancer, and the air transport of horses.

Morris Animal Foundation Chief Scientific Officer Janet Patterson-Kane said the charity was impressed with the quality of proposals. “We believe they have the potential to drive significant improvements in the well-being of our equine companions. We are very proud to support these enterprising researchers in their endeavors.”

Through this year’s grants, the Foundation is supporting teams at 13 universities and institutions. The Foundation’s Large Animal Scientific Advisory Board selected the studies with the greatest potential to save lives, preserve health and advance veterinary care.

Ashton Miller
Ashton Miller. © Jenny Evans, UK Gluck Equine Research Center
Research into immune function of PPID horses

Meanwhile, a recent study by Gluck’s Ashton Miller, PhD, examined various aspects of endocrine and immune function in aged horses with and without PPID. One of the main findings was that horses with PPID have altered immune function.

Miller recently finished her doctorate and a postdoctoral appointment, focusing on understanding how equine endocrine and immune function are impacted by pituitary pars intermedia dysfunction (PPID), also known as Equine Cushing’s Disease, which is common in older horses.

A major paper from her dissertation work has been published in Domestic Animal Endocrinology.

One of the key conclusions noted in the study is that resting ACTH, or adrenocorticotropic hormone, is likely the best choice for determining successful responses to treatment with pergolide. Neither PPID nor pergolide appeared to influence insulin, total cortisol and free cortisol. As measured, systemic immune function was altered in PPID horses, and it is likely that these horses are at increased risk of opportunistic infection. Despite reducing ACTH, pergolide treatment did not appear to influence immune function.

A key takeaway from the work done by Miller and the research team is that veterinarians and owners of PPID horses may benefit from increased biosecurity precautions when caring for PPID horses, particularly in higher-risk situations, such as transport, large gatherings or competitions. In addition, it is important for veterinarians and horse owners to recognize that PPID horses are likely at higher risk of opportunistic infection and to encourage regular testing for PPID in horses over the age of 15 years old to identify subclinical cases.

University of Kentucky College of Agriculture, Food and Environment.

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