87 How challenging is it to find non-insulin dysregulated horses in an apparently clinically healthy herd of university horses?

Abstract

Equine metabolic syndrome (EMS) is associated with insulin dysregulation (ID), basal/postprandial hyperinsulinemia, and/or tissue insulin resistance, and puts equids at higher risk of laminitis. In the past, EMS animals were typically considered to have regional (e.g., cresty neck score CNS ≥ 3/5) or general obesity (body condition score [BCS] ≥ 7/9). However, it has increasingly been recognized that lean animals can also be ID. Basal/post prandial hyperinsulinemia is determined using an oral sugar test (OST). ID status may affect investigation outcomes. To ensure non-ID horses were selected for a larger nutrition study, a herd of university horses was screened for ID. Twenty mixed breed, mature horses (mean ± SD; 15.8 ± 5.7 yrs.) with no history of laminitis and were considered clinically healthy with stable BCS ranging from 3.6 to 7.5/9 were screened for ID status based on the 2022 Equine Endocrinology Group Recommendations for Diagnosis and Management of EMS. Morphological measurements were also taken. Except for one horse, the herd had not been on a regimented exercise program for at least 5 mo. Blood samples were collected via jugular venipuncture before (T0) oral administration of Karo syrup lite (0.15mL/kg), and post-administration at 60 (T60) and 90 (T90) min. Serum was frozen until analysis for glucose and insulin (Antech Diagnostics, Fountain Valley, CA, USA). Data was analyzed using JMP and level of significance was setat P ≤ 0.05. BCS was not correlated with T0 insulin (R2 = 0.10, P = 0.17) but was correlated with CNS (R2 = 0.69, P < 0.001). Age was not correlated with T0 glucose (R2 = 0.02, P = 0.58) or insulin (R2 = 0.003, P = 0.82). The ID and non-ID populations differed in BCS (mean ± SD; 6.28 ± 1.01 vs 5.51 ± 0.87, respectively; Χ2, P = 0.045, Table 1), but due to considerable overlap in population ranges BCS alone was not sufficient to determine ID or non-ID status. Study limitations included a small sample size. This data supports the practice of using an OST to screen for ID status in potential research horses.