2017 ACVIM Forum Research Abstract Program

Twenty-three horses were assigned to IS (n = 13) and IR (n = 10) groups on the basis of frequently-sampled intravenous glucose tolerance tests and minimal model analysis, or fasted insulin concentrations. Humane euthanasia was performed for reasons other than this study, and pancreas samples were obtained for immunohistochemical analysis. Pancreas tissues were stained for insulin, glucagon and somatostatin and digital images were analyzed to determine expression of each hormone relative to total islet area. No significant differences in insulin staining were detected between groups and our hypothesis was not supported, but IR horses had a significantly less glucagon within pancreatic islets than IS horses. Median (interquartile range) percentage of total islet area staining positive for glucagon was 12% (5%, 13%) of total islet area in IR horses, compared to 18% (16%, 22%) in IS horses (P = 0.001). Immunoreactive glucagon, insulin, and somatostatin were present in approximately 15%, 63%, and 8% of total islet area, respectively.