Incidence of pregnancy loss and characterization of fetal development in red pandas

Abstract

Previous reports indicate that red pandas (Ailurus fulgens styani) may experience fetal loss during gestation; however, neither the rate nor timing of pregnancy failure has been described in this species. The objective of the current study was to utilize ultrasound video and images collected between 2010-2020 at the Cincinnati Zoo and Botanical Garden to better characterize pregnancy loss and fetal development. Trans-abdominal ultrasound examinations were performed on six female red pandas over a 10-year period, resulting in 12 profiles. Pregnancy was diagnosed via ultrasound in all profiles in which cubs were produced (n = 8) and in two profiles in which cubs were not produced. Two additional females did not produce cubs and no concepti were discernible via ultrasound. Fetal loss was documented in 40.0% of pregnancies and was classified into Lost (2 of 10; 20.0%), in which no cubs were produced, or Partial Loss (2 of 10; 20.0%), in which two concepti were visualized via ultrasound, but only one cub was born. Fetal loss occurred between days 51 and 23 pre-partum. Fetal growth characteristics were documented, including skeletal ossification (occurring between day 32 and 27 pre-partum), crown-rump length, head length, cranial length, and fetal heart rate (173-206 beats per minute). These findings provide novel insights into pregnancy loss, may serve as a reference for milestones of fetal development, and may be useful in diagnosing pregnancy and assessing pregnancy loss in red pandas.