The pathology of a case of biliary atresia in a foal.

This research article focuses on detailing the pathological features observed in a case of biliary atresia, a type of liver disease, in a one-month-old American Saddler foal. The presence of the disease was indicated by signs of liver failure and confirmed through autopsy, with important findings highlighting an unusually enlarged liver with an altered appearance, bile stasis, lack of large bile ducts, excess fluids in various body cavities, and replacement fibrosis.

Background Information

• Biliary atresia is a disease that primarily affects the bile ducts, which are the pathways through which bile is transported from the liver to the small intestine.
• Biliary atresia is severe and often life-threatening; it obstructs the flow of bile, leading to liver damage. Biomarkers indicative of this disease include features of liver failure.
• The foal in the case study was an American Saddler, a breed of horse, which was only 4 weeks old. Evidence of illness was visible, prompting the need for an autopsy.

Autopsy Findings and Diagnosis

• The main findings during the autopsy involved considerable alterations in the liver. These included extreme enlargement, mottling (blotchy or spattered appearance), and induration (hardening).
• Bile stasis was also evident. In this condition, the flow of bile is halted, leading to its accumulation and creating further complications.
• Larger bile ducts were found to be missing and lobular distinction, the division of a particular structure or space into smaller parts or sections, was absent – these are significant signs of biliary atresia.
• Fluid accumulation was noted in various parts of the foal’s body, which manifested as moderate ascites (fluid build-up in the abdomen), hydrothorax (in the chest cavity), and hydropericardium (around the heart). Mild anasarca (generalized edema) and intermuscular oedema were also reported.
• The diagnosis of biliary atresia was finally determined by observing the histopathological features. This included an abnormal proliferation of bile ducts and extensive replacement fibrosis, which involves the substitution of normal tissue with fibrous connective tissue.

Case Comparison and Conclusion

• The studied case was compared to anecdotal evidence of extrahepatic (outside the liver) and intrahepatic (within the liver) biliary atresia in humans.
• A conclusion was drawn, considering the symptoms and autopsy findings, that this case of biliary atresia in the foal originated from outside the liver (extrahepatic).

The research provides insight into how biliary atresia manifests in young horses, thereby contributing to veterinary knowledge and potentially guiding future diagnosis and treatment efforts for this disease.