Horse Hair Cortisol Concentration in University Owned Horses as a Potential Influence on Management Strategies

Cortisol is a hormone that is related to stress in animals. The ability to assess stress in animals could allow farm managers to modify animal management and improve animal welfare. As of a 2022 survey, Kentucky's equine industry combines to generate $6.5 billion in annual cumulative direct and indirect economic activity and a total of 60,494 jobs. Equine welfare often comes under public scrutiny, particularly in the racing industry, making it an important topic for stakeholders and legislators in Kentucky to be aware of. Serum cortisol is the gold standard for evaluating stress in horses. However, serum cortisol can be affected by circadian rhythms, environmental factors, and other excitatory factors, and it requires drawing blood from the horse. Cortisol in hair is less subject to these variables and is also less invasive to collect. As part of a larger project, the objective of this part of the study was to examine the impact of sample storage at room temperature (20 to 22° C) or in a freezer (-28.89° C) on hair cortisol concentrations. It was hypothesized that frozen samples would have better retention of cortisol and yield higher concentrations than samples kept at room temperature. Tail hair samples were collected from 32 University-owned horses in the spring and fall of 2024. Samples were split, with half being maintained at room temperature and the other half being frozen until analyzed. Samples were analyzed at the Breathitt Veterinary Center (Hopkinsville, KY, USA) using a corticosterone ELISA kit (Corticosterone Multi-Format ELISA Kit, Arbor Assays, Ann Arbor, MI, USA). This on-going study could improve horse owner and manager ability to identify stressed animals in a less invasive way, and allow them to modify management practices to improve equine welfare.