Gas-filled urachal abscess with a pinging sound in a heifer calf

A 6-month-old crossbred of a Holstein and Japanese Black heifer calf weighing 95 kg presented with a history of intermittent abdominal distension and failure to thrive. The physical examination identified a pinging sound over the dorsal left flank. The abdominal radiography showed a huge gas-filled mass. The intravenous urography revealed no communication between the mass and the urinary bladder. Although the visual examination and palpation of the umbilicus did not reveal visible abnormalities, an umbilical disease was suspected because the animal exhibited poor growth, depression, and a hunched back posture. When the eschar adhering to the centre of the umbilicus was removed, the presence of a fistulous tract was revealed. The umbilical ultrasound examination revealed an intra-abdominal abscess and the fistulography demonstrated that the abscess communicated with the umbilicus. The abscess, compressing into the rumen, was observed by computed tomography. From these images, it was diagnosed as an umbilical cord remnant abscess and a definitive diagnosis of a urachal abscess was obtained by open abdominal surgery and the subsequent removal of the mass. The calf was discharged from the university hospital on day 14 after the operation. This case shows that a urachal abscess should be considered when a pinging sound is present, even if the animal exhibits no swelling or pain of the umbilicus.