An 8-year-old castrated male mixed-breed cat presented with recurrent vomiting and weight loss. On physical examination, abnormalities included moderate icterus of the pinnae and mucus membranes. Blood work revealed elevated serum total bilirubin (Tbili), serum liver enzyme activities and serum amyloid A (SAA) protein (Table 1, day 0). SNAP feline pancreatic lipase immunoreactivity (fPLI) (Idexx Laboratories) was negative. The total thyroxine level was 2.36 μg/dl (reference interval [RI] 0.9–3.7 μg/dl). An abdominal ultrasound demonstrated dilation of both the intrahepatic and extrahepatic biliary tree (Figure 1a,b). The gallbladder could not be reliably identified from the abnormal surrounding ducts. The dilated biliary structures occupied the majority of the abdomen and revealed marked hyperechogenic sediment accumulation (Figure 1c). On abdominal CT scan, the intrahepatic bile ducts, cystic duct and CBD were markedly dilated and saccular in appearance. In particular, a fusiform dilatation of the CBD was observed. The duodenum was displaced to the left side by the dilated CBD. Findings of thickening and contrast enhancement of parts of the gallbladder wall and bile duct wall suggested cholecystitis and cholangitis. A definitive cause for the CBD obstruction was not identified on the CT scan (Figure 2).

The cat was diagnosed with obstruction of the CBD due to chronic cholangiohepatitis and was treated with enrofloxacin 5 mg/kg PO q24h, prednisolone 0.7 mg/kg PO q12h and metronidazole 10 mg/kg PO q12h. The medical treatment temporarily improved icterus and decreased the level of hyperbilirubinaemia (Table 1, day 7). However, after 2 weeks, surgical intervention was performed in the face of elevated TBili levels unresponsive to medical management (Table 1, day 14). The cat was premedicated with fentanyl 5 μg/kg IV and atropine 50 μg/kg IM, and induced with propofol 6 mg/kg IV. Anaesthesia was maintained with isoflurane vaporised in oxygen delivered with peak inspiratory pressures of 10 cm H₂O. Fentanyl was administered as a constant rate infusion (CRI) at a rate of 10 μg/kg/h. The patient was kept on a heating pad during surgery, with its vital parameters monitored every 5 mins. Surgical exploration of the abdomen revealed an enlarged gallbladder and dilated CBD that was severely thickened and fibrotic with omental and mesenteric adhesions (Figure 3). Upon performing a duodenotomy, it was confirmed that the major duodenal papilla was severely thickened, making catheterisation and flushing of the CBD impossible. As a result of marked dilation of both the intrahepatic and extrahepatic bile ducts, the distance between the duodenum and gallbladder was significantly increased, making cholecystoduodenostomy unfeasible. A choledochoduodenostomy using a simple side-to-side anastomosis between the CBD and duodenum was performed to relieve the CBD obstruction. The anastomosis was performed in the extramural CBD, approximately 5 cm distal to the major duodenal papilla. After placing two stay sutures to approximate the CBD and duodenum, an incision of approximately 3.0 cm was made in the extramural CBD and descending duodenum (Figure 4a,b). A simple side-to-side anastomosis between the CBD and duodenum was performed with 4-0 polydioxanone monofilament suture material in a simple continuous pattern (Figure 4c).

For biopsy, the margin of the quadrate lobe of the liver was excised using Metzenbaum scissors, and haemostasis was achieved with electrocautery. A wedge-shaped excision was made in the distal common bile duct wall, approximately 3 cm away from the major duodenal papilla, using a sharp blade scalpel. In addition, a biopsy of the gallbladder was performed using a 6 mm punch biopsy. The biopsy site was closed with simple interrupted sutures. A bile sample was also collected for bacterial examination, including aerobic/anaerobic culture and sensitivity testing. The peritoneal cavity was lavaged with warm sterile saline and then closed routinely. The cat was maintained on fentanyl CRI at 3 μg/kg/h for 24 h postoperatively. All medications, except for antibiotics (enrofloxacin 5 mg/kg PO q24h), were discontinued postoperatively.

Two days after surgery, abdominal ultrasound showed resolution of the previously noted dilation of the CBD, with no evidence of leaking bile (Figure 5). On blood work, Tbili was decreased (Table 1, day 16). One week postoperatively, the cat was discharged as it was voluntarily consuming over 80% of its resting energy requirement. At the time of discharge, no medications were prescribed except for antibiotics. Chronic suppurative cholangitis with infiltration of inflammatory cells was confirmed by histopathology of the liver tissue sample. Histopathology of the gallbladder sample revealed chronic neutrophilic proliferative cholecystitis. Bacterial colonies were not observed within the inflamed gallbladder tissue. Histopathology of the tissue taken from the obstructing site of the CBD demonstrated abundant dense fibrous connective tissue and infiltration of inflammatory cells. There was no evidence of neoplasia (Figure 6).

Follow-up examinations were performed 2 and 6 months postoperatively, during which time the cat remained clinically stable. Blood tests showed an improvement in hyperbilirubinaemia and liver enzyme activities (Table 1, days 46 and 194). On day 194, although a CT scan demonstrated gas in the gallbladder originating from the digestive tract, no evidence of anastomotic stenosis was observed (Figure 7).