2017 ACVIM Forum Research Abstract Program

Mane and tail hair from healthy broodmares (n = 10) was collected, segmented and analyzed. Additionally, yearling male (n = 14) and female horses (n = 14) were used. Separate mane and tail hair samples were collected at the beginning of the study (before castration) and 3 months after from male and female yearlings. Cortisol was extracted into methanol from ground hair and quantified using ELISA. HCC in mane samples from broodmares was greater than in tail samples. In all studied groups, segments further away from the hair root contained lower HCC. The decrease in hair cortisol concentrations between 1 and 2-months post-castration was significantly lower in castrated males than intact females. Cortisol accumulation in the month after castration could explain the significantly smaller decrease in HCC concentrations in males than females during the same time period. Results suggest that HCC analysis in horses can be used to address basal and elevated HPA activity in horses. Nevertheless, other factors such as segment location and collection site may also have an effect on measured HCC. Our group has demonstrated that up to 49% of Equine Metabolic Syndrome (EMS) phenotypic variability is explained by shared environment; however only 4-18% of this environmental variability is explained by diet, exercise and season, suggesting other environmental factors play a role in EMS. Endocrine Disrupting Chemicals (EDCs) are associated with metabolic syndrome and other endocrine abnormalities in humans, and our preliminary data demonstrated that horses from farms < 31 miles of EDC disposal sites (SF) were more likely to have had laminitis and had higher post oral-sugar-challenge insulin concentrations (INS-OST). These data suggested that EDC exposure is an EMS risk factor.