New study highlights risk of urolithiasis in dogs with primary portal vein hypoplasia

29 July 2026

Almost one-third of dogs diagnosed with primary portal vein hypoplasia develop urolithiasis, a new study has found, highlighting the importance of including urinalysis and diagnostic imaging in routine assessment of dogs with this condition.

Primary portal vein hypoplasia (PPVH) is a congenital vascular anomaly characterised by underdevelopment of the portal veins, leading to reduced blood flow to the liver. Little has previously been known about the prevalence and risk factors for urolithiasis in dogs with PPVH, or which dogs may be at greater risk.

The new study, by researchers at Southern Counties Veterinary Specialists and published in the Journal of Small Animal Practice, reviewed cases from 15 UK referral hospitals to assess the prevalence and clinical significance of urolithiasis in dogs diagnosed with PPVH.

The findings show that 29% of dogs with PPVH (4 dogs) developed urolithiasis. All affected dogs also had crystalluria, including three dogs with ammonium biurate crystals and one dog with bilirubin crystals. Among dogs diagnosed with urolithiasis, three had cystoliths, including one dog with concurrent multifocal obstructive ureterolithiasis.

Dogs with urolithiasis often had associated clinical signs. All affected dogs had gastrointestinal signs, while only half of the dogs had lower urinary signs such as haematuria or pollakiuria. Acquired extrahepatic portosystemic shunts were more common among dogs with urolithiasis and were found in half of dogs with urolithiasis, compared with 10% of dogs without. The results also suggest that urolithiasis may be less common in dogs with PPVH than in those with congenital portosystemic shunt.

These findings emphasise the importance of performing urinalysis and diagnostic imaging as part of the routine assessment of dogs with PPVH.

Read the full study in the Journal of Small Animal Practice: https://onlinelibrary.wiley.com/doi/10.1111/jsap.70157