A 7 year-old female spayed Presa Canario was presented to the Cornell University Hospital for Animals (CUHA) on 6/22/2011 after a 10-day history of vomiting, inappetence, and lethargy. The referring veterinarian had documented rising liver enzymes and suspected liver failure of unknown toxic cause. Initial diagnostics at CUHA confirmed increased hepatobiliary enzymes (ALT, AST, ALP, GGT), hyperbilirubinemia, hypercholesterolemia, hypoalbuminemia, and low BUN. Abdominal ultrasound revealed a gallbladder in the high-normal volume range at 2ml/kg and liver aspirates showed vacuolar degeneration of hepatocytes consistent with cholestasis. No evidence of bile duct obstruction was discovered and the dog was managed medically for non-specific infectious and toxic causes of acute liver disease. Liver values were monitored daily and continued to worsen while the dog also became depressed and anorexic and continued to vomit. The dog developed icterus and acholic feces. Repeat abdominal ultrasound was performed five days after admission and revealed an increased gallbladder volume to 3ml/kg and significant dilation of extra and intra-hepatic bile ducts. This information combined with worsening clinical signs and blood chemistry values justified exploratory laparotomy. The cause of bile duct obstruction was determined to be a cholelith within the ductus choledochus and choledocholithotomy and cholecystectomy were performed. The dog improved clinically and hematologically and was discharged from the hospital four days after surgery. The patient has been monitored by the referring veterinarian and continues to do well four months after surgery with the only abnormality being a mildly increased ALT.