Abstract: Background Early diagnosis of equine metabolic syndrome (EMS) and pituitary pars intermedia dysfunction (PPID) is associated with increased survival and improved quality of life. Diagnosis includes measurement of adrenocorticotropic hormone (ACTH) and insulin concentrations for PPID and EMS, respectively.
Hypothesis/Objectives To characterize the fluctuations in ACTH and insulin levels in healthy horses in Saskatchewan.
Animals Study 1: Fifty-two (n=52) client-owned horses. Inclusion criteria: no recent travel outside of Saskatchewan, normal physical exam findings, no history or evidence of ongoing illness. Study 2: Eighty (n=80) client-owned horses. Inclusion criteria: same as Study 1.
Methods: Study 1: Prospective, observational study. Blood samples were collected in spring and fall 2021, and ACTH and insulin concentrations were determined by chemiluminiscense. Univariable and multivariable linear regression models were used. Study 2: Prospective, observational study. Monthly sample collection started in July 2022 and will continue for a total of 12 months. Sample processing is the same as Study 1. Analysis will be performed with a generalized linear model.
Results: Study 1: ACTH and insulin levels increased in the fall compared to spring (p < 0.01). Age and fall ACTH levels were significantly associated (p = 0.005). Study 2: Data collection is ongoing. Preliminary results will be available by June 2023.
Conclusions and clinical importance Results so far highlight the seasonal trends in both ACTH and insulin levels in healthy horses in the Canadian Prairies. These results will help characterize fluctuations in these biomarkers, in order to better understand their regional behavior and improve diagnostic accuracy.
