Bile Duct Stenosis in a Free-Ranging Juvenile American Black Bear (Ursus americanus)

A free-ranging 10-month-old male American black bear (Ursus americanus) was presented to a rehabilitation facility in eastern Tennessee for being orphaned and emaciated, and was diagnosed with bile duct stenosis, leading to euthanasia. On initial intake, liver values including gamma-glutamyl transferase, alanine aminotransferase, and serum bile acids were elevated. The cub was treated for intestinal parasites and discharged to a rehabilitation facility for monitoring. Three weeks later, all liver values markedly increased despite improvements in body condition, appetite, and overall energy level. Abdominal ultrasound and dual phase computed tomography confirmed stenosis of the biliary outflow tract with gallbladder dilation and bile ducts in two locations. Surgical treatment and release were not performed due to the lack of clinical follow-up, likelihood of a genetic anomaly, and risk of it being passed to offspring. Necropsy findings further confirmed the bile duct stenosis with chronic regionally extensive fibrosis. The cause of this lesion is hypothesized to be congenital; however, inflammation secondary to a previous infection was not able to be ruled out. This case report documents the presentation and multidisciplinary approach to diagnosing a juvenile bear with bile duct stenosis, not previously reported in the literature.