Don’t Squeeze It! Transabdominal Ultrasound for Pregnancy Monitoring of a Trained Pygmy Hippopotamus (Choeropsis liberiensis)
2018 Joint EAZWV/AAZV/Leibniz-IZW Conference
Christian Wenker1*, Dr. med. vet, DECZM; Fabia Wyss1, Dr. med. vet, DACZM; Stefan Hoby2, Dr. med. vet, DECZM; Roland Schweizer1; Renate Vögtli, Dr. med. vet, DECVDI3
1Zoo Basel, Basel, Switzerland; 2Tierpark Bern, Bern, Switzerland; 3Kleintierpraxis Gundeli, Basel, Switzerland


Training was implemented for a female pygmy hippopotamus (Choeropsis liberiensis) to voluntarily enter a corridor. The corridor was accessible for an examiner from one side through vertical bars to provide protected contact. Front and back of the corridor remained open at all times so that the animal was able to quit the session whenever desired. Small vegetable items were fed to the animal to encourage it to stand in place during the procedures. The animal was desensitized to being touched by a gel-coated ultrasound probe (4C-RS, 2.0–5.0 MHz Convex, on a Logic V2, GE Healthcare ultrasound system, Buckinghamshire, Great Britain). Aggressive or other unwanted behavior was never observed. Weekly to bi-monthly transabdominal ultrasound examination was performed during two gestation periods of the same individual with a gestation length of 205 and 207 days, respectively. Each pregnancy resulted in the birth of a healthy female with a birth weight of 4.9 kg and 5.67 kg, respectively. Evidence of pregnancy was first observed on day 87 post-mating, while during the next weeks, fetal structures like cardiac activity, liver, and gallbladder, vena cava as well as cardiac chambers were identified, and their size determined (Table 1). Vulvar swelling was present 25 and 27 days antepartum and transabdominal fetal movements were palpable at the same time by placing a hand on the abdomen. Training pygmy hippos for minor procedures can be performed using simple designs of open corridors in protected contact. Holders are encouraged to train animals for this procedure in order to gain insight in physiological data of this species.

Table 1. First recognition of gestational signs using transabdominal ultrasound of fetal structures, visual inspection or palpation in a trained pygmy hippo

Sonographic recognition of fetal structures in a pygmy hippo

Day post mating (Measurements)



Fetal skeleton


Cardiac activity


Fetal orientation (head and body)

108 (skull diameter 44.7 mm, thoracal spine 48.6 mm, cervical spine 38.4 mm, abdomen length 90.3 mm, thorax diameter 46.9 mm)

Limb buds, fetal movement



108 (17.2 mm diameter)

Vena cava



108 (10.2 mm diameter)


108 (46.4 mm cross diameter)

Cardiac chambers


Other signs


Visual: Vulva edema


Palpation: Movements of fetus




*The presenting author is vet advisor of the pygmy hippo EEP


Speaker Information
(click the speaker's name to view other papers and abstracts submitted by this speaker)

Christian Wenker, Dr med vet, DECZM
Zoo Basel
Basel, Switzerland

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