Equine laminitis: induced by 48 h hyperinsulinaemia in Standardbred horses.

This research article investigates whether high levels of insulin in the bloodstream, also known as hyperinsulinaemia, can cause laminitis (a debilitating and painful condition) in healthy Standardbred horses. The study finds that prolonged hyperinsulinemia does result in laminitis within 48 hours, suggesting insulin as a trigger and emphasizing the importance of managing chronic hyperinsulinaemia.

Objective and Methods

• The study aimed to understand if hyperinsulinaemia could result in laminitis in Standardbred horses, a breed considered more insulin sensitive than ponies. The research also aimed to observe any correlation between hoof wall temperature changes and the onset of laminitis.
• The researchers utilized the prolonged euglycaemic hyperinsulinaemic clamp technique (p-EHC) on clinically normal Standardbred horses. Eight young horses, assigned into pairs, were divided into treatment (n = 4) and control (n = 4) groups.
• The treatment group horses were subjected to continuous infusions of insulin and glucose until signs of laminitis were visible, after which the horses were euthanized. Control horses received a balanced electrolyte infusion for the same duration.
• Throughout the experimental period, researchers continuously monitored the horses’ hoof wall surface temperature (HWST).

Results and Findings

• All treated horses, despite having normal insulin sensitivity, developed laminitis, while none in the control group did (P = 0.01).
• Horses in the treatment group were noted to have pronounced digital pulses, a sign of inflammation or trouble in the hoof, unlike the horses in the control group that exhibited insignificant digital pulses.
• The hoof wall surface temperature was consistently higher and less variable in the treated horses once hyperinsulinaemia was established.

Conclusions

• Standardbred horses, when subjected to prolonged hyperinsulinaemia, develop laminitis within 48 hours, thereby establishing a potent causative relationship between insulin and laminitis.
• The research evidently suggests that both horses and ponies are at risk of developing laminitis with insulin resistance and associated hyperinsulinaemia.
• The study underscores the urgency of managing persistent hyperinsulinaemia often observed in some endocrine disorders to prevent the onset of laminitis.