Identifying possible thresholds for nonstructural carbohydrates in the insulin dysregulated horse.
Authors: Macon Erica Lyn, Harris Patricia, Bailey Simon, Caldwell Barker Ashley, Adams Amanda
Journal: Equine veterinary journal
Summary
# Editorial Summary Hyperinsulinaemia-associated laminitis remains a significant concern in insulin dysregulated (ID) horses, yet practical guidance on safe carbohydrate thresholds has been limited. Macon and colleagues conducted a randomised crossover trial feeding 14 weight-matched horses (6 ID, 8 metabolically normal) eight different diets built on a low-NSC pellet base, with titrated additions of pure dextrose or starch to create NSC loads ranging from baseline to 0.17 g water-soluble carbohydrates (WSC) per kg bodyweight or 0.1 g starch per kg bodyweight. Whilst non-insulin dysregulated horses showed no significant dietary effect on insulin response, ID horses demonstrated substantially augmented postprandial insulin curves (measured as incremental area under the curve) when NSC exceeded approximately 0.1 g/kg bodyweight per meal compared with the low-NSC control (p <0.05), with ID responses diverging significantly from normal horses at this threshold. For practitioners managing laminitis-prone or metabolically susceptible horses, these findings suggest keeping NSC below 0.1 g/kg bodyweight per individual meal—a practical threshold translating to careful scrutiny of concentrate composition and portion sizes rather than reliance on forage alone. However, the use of purified starch and sugar sources means individual variation between horses and the insulin response to natural feeds warrants ongoing monitoring; additional research evaluating whole-feed scenarios and longer-term metabolic stability would strengthen clinical application.
Read the full abstract on PubMed
Practical Takeaways
- •Keep total NSC intake below 0.1 g/kg bodyweight per meal for insulin dysregulated horses to minimize laminitis risk; this translates to roughly 5 g NSC per 500 kg horse per feeding
- •Use of low-NSC pelleted feeds as a base diet, with careful titration of any supplemental carbohydrate sources, allows better control of postprandial insulin spikes in ID horses
- •Not all horses respond equally to carbohydrate restriction—monitor individual insulin responses rather than applying blanket dietary rules to all horses on your property
Key Findings
- •ID horses showed significantly augmented insulin responses to diets containing nonstructural carbohydrates >0.1 g/kg bodyweight compared with low-NSC baseline diet (p<0.05)
- •Non-insulin dysregulated horses showed no significant dietary effect across all NSC levels tested
- •An apparent threshold for NSC intake in ID horses is approximately 0.1 g/kg bodyweight per meal, above which exaggerated insulin responses occur
- •Thresholds varied between pure sugar and pure starch sources when added to the base low-NSC diet