Horses with previous episodes of laminitis have altered insulin responses to seasonal oral sugar testing and grazing compared to horses with no known history of laminitis.

This research article examines the influence of a history of laminitis on a horse’s metabolic and morphometric responses when grazing. The study found that horses which had previously had laminitis often exhibit greater insulin concentrations when grazing and during an oral sugar test.

Research Methodology

• The research was conducted on twelve non-pregnant mares, split into two groups – those with a previous diagnosis of laminitis (PRELAM) and those without (NOLAM).
• The horses were maintained on an 8.5-hectare pasture, and weekly pasture samples were randomly taken for nutrient analysis.
• Glucose and insulin levels were monitored monthly through blood samples, in addition to the body weight, body condition score (BCS), and cresty neck score (CNS).
• A modified oral sugar test (OST) was conducted every month to assess the basal and 75-minute insulin dynamics after administering 0.30 mL/kg body weight of Karo Light Corn Syrup.

Findings

• The PRELAM group had notably higher CNS, body weight, and body condition scores compared to the NOLAM horses.
• Non-fasted glucose levels were influenced by the month, indicating a seasonal variation in baseline glucose levels.
• Non-fasted insulin levels also showed variation across months, but there was a significant group to month interaction. This means monthly variation in non-fasted insulin levels was different between the PRELAM and NOLAM groups.
• Fasted insulin levels (T0) were affected by both the month and the group, with PRELAM horses showing higher concentrations.
• T75 glucose and insulin concentrations varied by month and were found to be higher in PRELAM horses, signifying a potential laminitis-induced alteration in insulin dynamics during the 75-minute window post-sugar administration.

Conclusion

• The prevalent finding of the study is that horses with greater general and regional adiposity (as represented by body weight and BCS), and a previous history of laminitis, frequently exhibit higher insulin concentrations while on pasture and during an OST. This discovery has profound implications for managing equine health, particularly in horses recovering from laminitis.