Computed Tomography Angiography Diagnosis of a Congenital Intrahepatic Central Divisional Portocaval Shunt in an Arabian Filly

A 1-month-old Arabian filly presented for central neurologic signs that developed shortly after birth. Hyperammonemia and elevated bile acids were identified, prompting abdominal computed tomography angiography (CTA) evaluation on suspicion of congenital portosystemic shunting (PSS). CTA revealed an anomalous vessel connecting the intrahepatic central divisional portal branch and caudal vena cava, with microhepatica and bilateral renomegaly. Necropsy confirmed a single, congenital, and intrahepatic central divisional portocaval shunt. Imaging literature addressing PSS in foals is sparse, with the current case representing the first instance in which CTA alone was fully diagnostic of an intrahepatic shunt in a foal.