Ionised hypercalcaemia in a cat with extrahepatic biliary tract obstruction secondary to a bile duct vegetal foreign body

Case summary A 10-year-old neutered female domestic shorthair cat was presented to our hospital with a 2-day history of anorexia, vomiting and lethargy. The biochemistry panel revealed increased hepatic enzyme activity and serum amyloid A concentration. Haematological values were within reference intervals. An abdominal ultrasound identified a hyperechoic spindle-shaped structure within the common bile duct and a suspected secondary subobstruction, associated with signs of intra- and extrahepatic biliary tract inflammation. During hospitalisation, the cat developed severe and sustained ionised hypercalcaemia. Exploratory surgery was elected as a result of the lack of clinical improvement, despite supportive treatment and suspected retrograde migration of the spindle-shaped structure. Two grass awns were extracted at the junction of an extrahepatic duct and the common bile duct via choledochotomy using intraoperative ultrasound guidance. A stent was then placed in the bile duct to prevent subsequent bile leakage. Histopathology of the liver revealed a moderate neutrophilic and lymphoplasmacytic inflammation with rare bacterial colonies. Escherichia coli was cultured from a bile sample. No specific cause of hypercalcaemia was identified. The cat recovered uneventfully from surgery. Hepatic enzyme activities and hypercalcaemia progressively decreased within a few weeks after surgery and remained within the reference intervals without treatment. Therefore, hypercalcaemia was suspected to be secondary to a foreign body-related granulomatous reaction. Relevance and novel information To our knowledge, only one other feline case report of biliary tract obstruction secondary to a biliary foreign body has been described in the literature. This is also the first case reporting the use of intraoperative ultrasound to localise a vegetal foreign body within the biliary tract of a cat. This case is also unique because of the onset of hypercalcaemia suspected to be secondary to a foreign body-related granulomatous reaction.