New research, conducted in collaboration with Spillers equine nutrition, shows that even healthy old horses have increased insulin responses compared to younger equids in response to a starch rich or starch and sugar rich meal.
This suggests that older horses, whether or not they have been diagnosed with insulin dysregulation, need an appropriate diet and management plan to help minimize the risks associated with insulin dysregulation such as laminitis.
The hormone insulin is produced by the pancreas. When insulin is released, cells (especially in muscle and the liver) are signaled to take up glucose from the blood. A high level of insulin in the blood (hyperinsulinemia) could be accompanied by insulin resistance (failure of cells to respond appropriately to insulin). This is why the term insulin dysregulation is now used; it refers collectively to excessive insulin responses to sugars, and/or fasting hyperinsulinaemia and/or insulin resistance.
Researchers at the Waltham Centre for Pet Nutrition, in Leicestershire, England, which provides the science underpinning the Spillers brand, and Michigan State University, in East Lansing, conducted two studies to learn more about the relationship between insulin dysregulation, dietary adaptation, and aging to help guide more appropriate senior horse feeding regimens.
In both studies researchers investigated tissue insulin resistance and the insulin response in healthy adults compared to healthy old horses adapted to diets with varying levels and sources of hydrolysable and structural carbohydrate (starch, sugar, and fiber).
Results from both studies showed insulin responses tend to increase with age in healthy horses, regardless of the diet they had been fed prior to evaluation. The insulin response, for example, was highest in the old horses fed a starch rich meal even when they had been adapted to such a diet.
“These studies confirm that even healthy older horses can have an increased insulin response compared to younger animals,” said Clare Barfoot, BSc (Hons), RNutr, the research and development manager at Spillers. “This suggests that the energy sources used in the diet of senior horses and their effect on insulin dynamics need to be carefully considered. Practically, this means restricting the overall amount of starch and sugar in the diet especially for those horses that already have additional risk factors such as obesity, native breeding, or PPID (pituitary pars intermedia dysfunction).”
- Rapson JL, Schott II HC, Nielsen BD, McCutcheon LJ, Harris PA, and Geor R.J. (2018) Effects of age and diet on glucose and insulin dynamics in the horse. Equine Vet J.
- Jacob SI, Geor RJ, Weber PSD, Harris PA, and McCue ME. (2018) Effect of age and dietary carbohydrate profiles on glucose and insulin dynamics in horses. Equine Vet J. 50: 249 – 254.