Cortisol, progesterone, 17αOHprogesterone, and pregnenolone in foals born from mare's hormone-treated for experimentally induced ascending placentitis.

Abstract

This study aimed to evaluate steroid hormones in foals born from mares treated for ascending placentitis with different combinations of trimethoprim-sulfamethoxazole (TMS), flunixin meglumine (FM), long-acting altrenogest (ALT) and estradiol cypionate (ECP) for ten consecutive days, starting two days after experimental induction of placentitis with Streptococcus zooepidemicus. Fourty-six pregnant mares and respective foals were assigned as healthy group (Control, n&#xa0;=&#xa0;8) or treated groups as follows: TMS+FM (n&#xa0;=&#xa0;8), TMS+FM+ALT (n&#xa0;=&#xa0;8), TMS+FM+ALT+ECP (n&#xa0;=&#xa0;6), TMS+FM+ECP (n&#xa0;=&#xa0;6) and no treatment (NO TREAT n&#xa0;=&#xa0;10). At delivery, foals were classified as high-risk or low-risk based on clinical and hematologic findings, and survival rates were recorded during the first week of life for comparisons across groups. Cortisol, progesterone, 17&#x3b1;OHprogesterone, and pregnenolone concentrations were determined via immunoassays in 31 of the 46 foals immediately after foaling (0&#xa0;h), at 12, 24, 48&#xa0;h, and seven days post-partum (168h). At birth, serum cortisol concentrations were higher in Control and TMS+FM+ECP foals than in remaining groups (p&#xa0;<&#xa0;0.05). Foals in TMS+FM+ALT and TMS+FM groups had higher 17&#x3b1;OHprogesterone concentrations at 24&#xa0;h and 48&#xa0;h, respectively (p&#xa0;<&#xa0;0.05). Pregnenolone concentrations were higher in TMS+FM than TMS+FM+ALT+ECP foals at 7 days (p&#xa0;<&#xa0;0.05). High-risk and non-surviving foals had decreased concentrations of cortisol at parturition, but increased concentrations of progesterone from 0&#xa0;h to 48&#xa0;h. Pregnenolone and 17&#x3b1;OHprogesterone concentrations were increased and pregnenolone after 12&#xa0;h in high-risk and non-surviving foals (p&#xa0;<&#xa0;0.05). In conclusion, adding ECP to the treatment of experimentally-induced placentitis appears to improve foal viability and endocrine response. Cortisol and progestogen profiles were abnormal in high-risk and non-surviving foals, and those treated with ALT or TMS+FM only.