Keeper staff at the Wildlife Conservation Society’s Bronx Zoo trained an adult female okapi (Okapi johnstoni) to facilitate transabdominal ultrasound examination by veterinary staff. A horizontally barred gate was constructed to replace a solid stall door during ultrasound examination. The animal was encouraged with food to position her body within two feet of and parallel to the gate. The animal was acclimated to ultrasound gel by the keepers utilizing alcohol, gel, and a substitute probe until the animal adjusted to and allowed the procedure. Training was performed over a period of 4 weeks prior to the initial ultrasound examination.
Serial ultrasound examinations were performed every 2 weeks from 6 months post-breeding through parturition (14-month gestation). An Aloka 500V ultrasound machine with a 3.5 MHz “backfat” probe (Corometrics Medical Systems, Inc., Wallingford, CT, USA) was utilized, and the sessions were videotaped. The ultrasound probe was placed on the caudal and lateral abdomen. The heart, liver, ribs, and vertebrate of the fetus were visualized at the majority of the procedures. Cardiac measurements were obtained when possible and used to document growth and health of the fetus. The placental cotyledons of the dam were readily visualized. Ultrasound images were obtained from both sides of the abdomen.
In addition to obtaining measurements, this training allowed assessment of fetal health during periods of concern. At 8 months of gestation, abnormal behavior, gait, and evidence of discomfort were apparent. Transabdominal ultrasound allowed for confirmation of fetal vitality in a rapid, minimally stressful, and noninvasive manner.