Abstract
Objective—To evaluate the effects of endotoxin administered IV on glucose and insulin dynamics in horses.
Animals—16 healthy adult mares.
Procedures—Each week of a 2-week randomized crossover study, each horse received an IV injection (duration, 30 minutes) of Escherichia coli O55:B5 lipopolysaccharide (LPS) in 60 mL of sterile saline (0.9% NaCl) solution (20 ng/kg) or sterile saline solution alone (control treatment). Frequently sampled IV glucose tolerance test procedures were performed at 24 hours before (baseline) and 24 and 48 hours after injection; glucose and insulin dynamics were assessed via minimal model analysis.
Results—13 of 16 horses had a clinical response to LPS, which was characterized by mild colic and leukopenia. Before treatment, mean ± SD insulin sensitivity was 2.9 ± 1.9 × 10−4 L·min−1·mU−1; this significantly decreased to 0.9 ± 0.9 × 10−4 L·min−1·mU−1 24 hours after treatment (69% reduction) and was 1.5 ± 0.9 × 10−4 L·min−1·mU−1 48 hours after treatment. At baseline, mean ± SD acute insulin response to glucose was 520 ± 196 mU·min·L−1; this significantly increased to 938 ± 620 mU·min·L−1 (80% increase) and 755 ± 400 mU·min·L−1 (45% increase) at 24 and 48 hours after LPS treatment, respectively.
Conclusions and Clinical Relevance—Compared with baseline values, insulin sensitivity was decreased for 24 hours after IV injection of LPS, and affected horses had a compensatory pancreatic response. These disturbances in glucose and insulin dynamics may contribute to development of laminitis in horses.
