Sonographic parameters for assessment of fetal well-being in mid-gestation in german Thoroughbred mares

Abstract

Summary: Sonographic parameters were studied in healthy Thoroughbred mares (n = 286) in mid-gestation (day 84 -232), and included: combined thickness of uterus and placenta (CTUP), echogenicity of the allantoic fluid (ALF), presence of free floating particles (FFP), and the fetal heart rate (FHR). In case of an abortion or stillbirth, data of the sonographic parameters were compared with results from necropsies. Abnormalities in CTUP values were seen in 18 cases (maximum value of 17.7 mm). The sonographic appearance of ALF did not change during gestation. There was a significant difference in the presence of FFP with respect to the month of gestation. Abortion rates were determined to be 6.33 times higher for mares with presence of FFP. The mean FHR decreased significantly during gestation. In 7 mares a fetal bradycardia was found, while in 14 mares a tachycardia was found. Overall, 13 abortions (4.8 %) occurred between 201 and 315 days of gestation, which was about 94 ± 46.1 days after the sonographic examination. In one case of an abortion, an abnormal CTUP (8.9 mm), and in another case an abnormal FHR (170 beats/min) was determined. In the remaining 11 cases no abnormalities were detected during sonographic examinations. Although deviations from mean values for sonographic parameters do not necessarily result in an abortion or stillbirth, such abnormalities should be taken seriously and continuously monitored. We conclude that the month of gestation affects FFP as well as FHR in Thoroughbred mares. Furthermore, sonographic evaluation of CTUP, FFP, and FHR alone is not sufficient to foresee placental failure and impending abortion.Keywords: horse / pregnancy / ultrasound / placentitis / combined thickness of uterus and placenta / abortion / reproduction Citation: Seehafer H., Oldenhof H., Kassens A., Klewitz J., Ulrich R., Martinsson G., Rohn K., Baumgärtner W., Sieme H. (2015) Sonographic parameters for assessment of fetal well-being in mid-gestation in german Thoroughbred mares. Pferdeheilkunde 31,[477][478][479][480][481][482][483][484]