Serum cortisol and thyroid hormone concentrations and survival in foals born from mares with experimentally induced ascending placentitis

Abstract

Background: There are few publications on occurrence of nonthyroidal illness syndrome in foals and on the prognostic value of cortisol and thyroid hormone (TH) concentrations in newborn foals. Objectives: To determine serum cortisol and TH concentrations (total and free thyroxine: T4 and FT4; total and free triiodothyronine: T3 and FT3) in foals born from mares with placentitis, to determine their association with survival, and their use as prognostic markers. Animals: A cohort of 29 newborn foals comprising 5 Control, 14 Low-risk, and 10 Sick foals were evaluated over the first week of life. Methods: In this prospective study foals born to mares with experimentally-induced placentitis were assigned to Low-risk or Sick groups while foals born to control mares were classified as Control based on clinical findings. Foals were also classified as Term (n = 13), Dysmature (n = 7), or Premature (n = 9), and survival rate was recorded. Serum cortisol and TH hormone concentrations were measured at 0, 12, 24, 48, and 168 hours of life. Results: Sick non-surviving foals had lower (P