Seasonal Insulin Responses to the Oral Sugar Test in Healthy and Insulin Dysregulated Horses.

The research examines how seasonal changes might affect the results of the Oral Sugar Test (OST), a test used in horses to monitor insulin regulation and lower the risk of laminitis. It concludes that, while there may be some seasonal fluctuations the OST is a reliable method to diagnose insulin dysregulation in horses, irrespective of the season.

Research Subject and Methodology

• The study was conducted over a period of 2 years and involved both insulin dysregulated (ID) and non-insulin dysregulated (NID) horses. The ages of the horses were similar, with a mean age of approximately 15 years.
• The horses were subjected to the Oral Sugar Test (OST), where they were given a specific quantity of Karo Light Corn Syrup. This is a test commonly used to monitor insulin dysregulation in horses.
• The researchers collected seasonal morphometric measurements such as bodyweight, body-condition scores, and cresty neck scores, which provide a subjective assessment of the horse’s fat deposition and overall health condition.
• The researchers also considered the forage the horses consumed, collecting and analyzing samples from paddocks and hay for each season.
• A statistical software was used to analyze the collected data.

Main Findings

• The study found no seasonal effect on the body weight of the horses.
• The insulin dysregulated (ID) horses had higher body-condition scores and cresty neck scores in the spring, summer and fall compared to those without insulin dysregulation (NID). This suggests that ID horses may have higher fat deposition and overall poorer health condition in those seasons.
• The analysis of the paddock (grazing area) showed variations across seasons, while the hay didn’t show significant seasonal differences.
• Insulin levels in ID horses were consistently higher at both resting (T0) and after 60 minutes of performing OST (T60) across all seasons. Moreover, these horses showed a higher increase in insulin levels in the spring as compared to other seasons. In NID horses, there were no significant seasonal changes in T0 insulin levels, but there was a higher insulin response to OST in spring versus summer.
• Approximately 56% of ID horses confirmed their insulin dysregulation status based on their resting insulin levels (T0). However, using the 60-minute post-OST measurements (T60), this consistency increased to 94%, confirming the OST as a reliable diagnostic tool for insulin dysregulation.

Conclusion

• The primary takeaway from this study is that while there may be some seasonal variations in certain health indicators, the Oral Sugar Test (OST) consistently identifies insulin dysregulation in horses, irrespective of the season.
• Hence, despite seasonal changes in horses’ conditions, OST can be reliably used for diagnosing insulin dysregulation and managing associated health risks such as laminitis.