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

## TL;DR

A young wild American black bear was euthanized due to severe bile duct narrowing, a condition not previously seen in wild bears, after it failed to improve despite treatment.

## Contribution

This is the first documented case of bile duct stenosis in a free-ranging wild bear, offering new insights for wildlife health management.

## Key findings

- Bile duct stenosis was diagnosed in a juvenile American black bear using advanced imaging techniques.
- Necropsy confirmed chronic fibrosis and stenosis, suggesting a possible congenital cause.
- The bear's condition did not improve despite treatment for parasites and rehabilitation efforts.

## Abstract

This report describes the case of a juvenile American black bear that was found alone and in poor health in eastern Tennessee. The bear was taken to a rehabilitation center, where it was discovered to have abnormally high liver values on bloodwork. Despite treatment for parasites and some initial improvement in its general condition, serial blood tests revealed progressively worsening liver values. Advanced diagnostic imaging confirmed severe narrowing of the bile ducts, which deliver bile from the liver to the intestines to aid in digestion, and gallbladder dilation. Due to poor prognosis for surviving in the wild and the possibility of passing the trait to offspring if treated with surgery and released, the bear was euthanized. Necropsy confirmed the findings of biliary stenosis and suggest a possible congenital cause or less likely due to a past infection. This report is important because it is the first time such a condition has been described in a wild bear, providing new information for wildlife health experts. Understanding rare conditions like this, and how they were diagnosed, can help improve care for wild animals and support better wildlife management.

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.