Being obese and/or having abnormal insulin responses (insulin dysregulation or ID) is thought to increase the risk of laminitis.  Obesity is often associated with ID in certain breeds, but are there breed differences in insulin responses regardless of body condition? In this study, researchers at the University of Melbourne, Australia investigated whether breed contributes to ID in non-obese horses.
 

Read more below about this exciting research.
 

Objectives:
 

To compare glucose and insulin responses of Andalusians, Standardbreds and ponies through the use of two different glucose tolerance tests.
 

Horses:
 

8 Standardbreds, 8 mixed-breed ponies, and 7 Andalusian-crosses averaging a body condition score of five. The Andalusians and ponies were chosen for this study as examples of “easy-keepers”. Horses were kept in dry paddocks with ad libitum access to grass hay.
 

Glucose Tolerance Tests:
 

  1. Oral Glucose Tolerance Test (OGTT): After a baseline blood sample was drawn, the horses consumed a meal containing 1.5g of glucose per kilogram body weight. Blood samples then collected at regular intervals for six hours post-meal to observe changes in glucose and insulin levels.
  2. Frequently Sampled Intravenous Glucose Tolerance Test (FSIGT): After a baseline blood sample was drawn, a glucose bolus (300 mg/kg of body weight) was administered followed 20 minutes later by an insulin bolus (20 mIU/kg bodyweight). Blood samples then collected at regular intervals for six hours post-administration.


Results:
 

  • Insulin peaked at a higher level in ponies and Andalusians compared to Standardbreds in the OGTT.
  • Ponies and Andalusians showed reduced sensitivity to insulin compared to Standardbreds in the FSIGT, meaning more insulin was necessary to return rising blood glucose levels to normal.


Take Home Message:
 

Breed should possibly be taken into account when choosing a diet for horses and ponies in order to help reduce the risk of obesity, equine metabolic syndrome and possibly laminitis.