2016 ACVIM Forum Research Abstract Program

Sian Durward-Akhurst 1 , Nichol Schulz 1 , Elaine Norton 1 , Raymond Geor 2 , James Mickelson 1 , Molly Mccue 1 . 1 University of Minnesota, MN, USA, 2 Mmassey University, Palmerston North, New Zealand Equine Metabolic Syndrome (EMS) is characterized by abnormalities in insulin regulation, increased adiposity and laminitis. In a large across-breed study (610 individuals) of 11 morphometric and biochemical metabolic traits, our lab has demonstrated that 51-77% of the phenotypic variability is due to individual factors including age, breed, sex and genetics and 23-49% of the phenotypic variability is the result of shared environment. Despite up to 49% of the variability in EMS phenotype being related to shared environment; only 4-18% of this variability is explained by diet, amount and intensity of exercise and season, suggesting that other environmental factors play a role in EMS development. Recent work has identified associations between Endocrine Disrupting Chemicals (EDCs) and human metabolic syndrome and other endocrine abnormalities. Our preliminary data demonstrated that horses from farms within 30 miles of EDC disposal sites (EPA "Superfund sites") were more likely to have had laminitis (P = 0.002) and had higher post oral sugar challenge insulin concentrations (OST INS) (P = 0.00005), suggesting EDC exposure is an EMS risk factor. The objective of this study was to determine if plasma EDC concentration is correlated to metabolic measurements. Plasma EDC concentrations were measured using the CALUX-DR bioassay in 158 Morgans and 137 Welsh Ponies from 32 farms. Grams fat extracted from plasma and sex (female) were negatively correlated with EDC concentration. EDC concentration was positively associated with OST INS (P = 0.03). The results suggest that some of the unexplained environmental variance identified in individuals with EMS is due to exposure to EDCs. Veterinarians have identified equine metabolic syndrome (EMS) as the most common cause of laminitis within equine practice. An oral sugar test (OST) has been used clinically to identify "at risk" horses although it has not been rigorously compared to a "gold standard" frequently sampled intravenous glucose tolerance test (FSIGTT) in a large number of horses or across different breeds.