Ultrasonographic measurement of fetal growth parameters over three successive pregnancies in a captive Malayan tapir (Tapirus indicus).

Abstract

This study was conducted to establish representative curves that allow evaluation of fetal growth and estimation of gestational age from measurement of fetal structures by ultrasound in Malayan tapirs (Tapirus indicus). Three pregnancies (i.e. 3 fetuses) were examined in one female Malayan tapir. Transabdominal ultrasonographic examination was performed without anesthesia from 79 ± 8 days to 281 ± 48 days (mean ± S.D.) post mating. To assess fetal growth attempts were made to measure biparietal diameter (BPD), head length (HL), thorax diameter A (TDA), thorax height A (THA), thorax diameter B (TDB), thorax height B (THB), abdomen diameter (AD), abdomen height (AH), humerus length (HUL) and Crown rump length (CRL). The value of each parameter as an estimator of gestational age was assessed by ease of observation and the length of time the parameter was measurable throughout gestation. The most precise predictors for gestational age in this study were BPD and CRL (weeks 10-20 of gestation), as well as AD and AH (weeks 14-43 of gestation). The parameters TDB, THB and HUL (weeks 15-41 of gestation) gave almost as good predictions. Fetal viability was assessed by identifying a fetal heartbeat and movement. All pregnancies resulted in normal deliveries and healthy offspring. The ultrasound examination was well tolerated by the female. The gestation lengths (399 ± 3 days) were within reported ranges. The serial transabdominal ultrasound, without the need for anesthesia, was an effective method to evaluate fetal growth, development and well being in a Malayan tapir.