Estratégias de diagnóstico e tratamento da gestação de risco em éguas

Abstract

Ascending placentitis is one of the main causes of abortion, stillbirth and premature labor in the equine species. Plasma hormone concentrations have been used to aid in the diagnosis and therapeutic management of placentitis. Few molecules have been assessed regarding its diffusion through the placenta and suitability in the treatment of this pathology.The aims of this study were: (1) to verify placental diffusion of doxycycline in healthy mares; (2) to assess the usefulness of 17-β estradiol, progesterone, progestins and total estrogens concentrations as pregnancy prognostic markers in mares with experimentally induced ascending placentitis. For the first experiment, twelve healthy mares were enrolled in this study at 320 days of gestation; six received compounded doxycycline (10mg/kg, PO, q12h) until delivery, while six were the control group. Foaling of the treated group was induced with oxytocin (10IU, IM) when mammary secretion pH was ≤6.4. During second stage of labor, allantoic fluid was collected by free catch and amniotic fluid by puncture. Blood and synovial fluid samples from foals were collected immediately after parturition. Concentrations of doxycycline in plasma and fetal fluids were assessed with LC-MS/MS. As for the second experiment, on the 300th day of pregnancy, mares were randomly divided into a healthy control group (CONT, n=8) and mares in which ascending placentitis was experimentally induced via intracervical inoculation of Streptococcus equi subspecies zooepidemicus (n=38). Mares with experimentally induced placentitis were assigned to groups treated with sulfamethoxazole-trimethoprim (TMS), flunixin meglumine (FM), altrenogest (ALT), and/or estradiol cypionate (ECP) as follows: (1) TMS+FM, n=8; (2) TMS+FM+ALT, n=8; (3) TMS+FM+ALT+ECP, n=6; (4) TMS+FM+ECP, n=6; and (5) no treatment (INOC, n=10). Treatment was started 48h after inoculation. Blood samples were obtained from all mares immediately prior to inoculation, daily for 12 days (or until premature delivery) and on foaling day. 17-β estradiol and progesterone concentrations were determined by chemiluminescence, whilst total estrogens and progestins were assessed via radioimmunoassay. Doxycycline crosses the equine placenta, reaches the fetoplacental unit and accumulates on foals’ synovial fluid. Neither mares nor foals presented any clinical signs suggestive of doxycycline toxicity, despite prolonged usage of this antimicrobial. In the present study, 17-β estradiol, progesterone, progestins and total estrogens concentrations lacked a pattern that could indicate pregnancy prognosis.