Gastric lactophytobezoar causing pyloric outlet obstruction in a pygmy hippopotamus calf ( Choeropsis liberiensis )

A one-month-old, female, mother-reared pygmy hippopotamus, Choeropsis liberiensis, died under anaesthesia after presenting with acute-onset regurgitation of milk. Abdominal radiographs revealed a radiodense mass within the stomach, which on postmortem examination was found to be a large, solid, stratified lactophytobezoar causing pyloric outlet obstruction. Lactobezoars are gastric concretions formed from solidified, undigested milk, sometimes mixed with mucus. When mixed with plant material, they are referred to as lactophytobezoars. Histopathology revealed aspiration pneumonia and erosive and suppurative tracheitis. Lactobezoars are diagnosed most commonly in premature human infants and have been reported occasionally in hand-reared felids and ursids. To the authors’ knowledge, this is the first report of a lactophytobezoar in a non-human mammal reared on its mother. Lactobezoars and lactophytobezoars should be considered in the list of differential diagnoses for emesis, regurgitation or abdominal mass in any milk-fed mammal, whether hand or parent-reared.