EXPRESS: Subclinical Primary Portal Vein Hypoplasia in a Cat: Early Diagnosis Through Computed Tomography and Histopathology

Case summary: Primary portal vein hypoplasia (PVH) is a rare congenital vascular disorder characterized by underdevelopment of the portal veins, leading to hepatic hypoperfusion and hypoplasia of the affected liver lobes. Although PVH is occasionally diagnosed in dogs, its occurrence in cats is exceptionally rare, with only a few cases reported. This case report describes the early detection of PVH in a 1-year-old female Russian Blue cat that exhibited persistently elevated liver enzyme levels without any clinical signs. Computed tomography (CT) imaging revealed hypoplasia of the left portal branch and a reduction in the volume of specific liver lobes. Histopathology confirmed PVH, revealing hypoplastic portal veins, mild bile duct and arteriolar hyperplasia, and hepatocellular vacuolar degeneration. The cat remained asymptomatic during the 18-month follow-up period.