Subclinical primary portal vein hypoplasia in a cat: early diagnosis through CT and histopathology.

Case summary: Primary portal vein hypoplasia (PVH) is a rare congenital vascular disorder characterised 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 activity without any clinical signs. 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. Relevance and novel information: This case highlights the critical role of advanced imaging modalities, particularly CT, in the early diagnosis of PVH in cats and emphasises the potential for early intervention in asymptomatic cases. These findings contribute to the limited body of knowledge on feline PVH, expanding the understanding and paving the way for further research into its prevalence, pathophysiology and optimal diagnostic approaches in veterinary practice.