Successful nutritional management of ammonium urate urolithiasis in an adult cat with congenital portosystemic shunt: A non‐liver diet approach

Abstract Congenital portosystemic shunts are rare vascular anomalies in cats that divert portal blood away from the liver, leading to hepatic hypoplasia and metabolic dysfunction. This case report describes the nutritional management of a 1‐year and 8‐month‐old cat diagnosed with an inoperable, multifocal, extrahepatic congenital portosystemic shunt and recurrent ammonium urate urolithiasis. A dietary transition from a soy‐based diet to an extruded hypoallergenic diet containing egg, pea and insect protein significantly reduced purine and copper intake while maintaining hepatic support. Additionally, lactulose supplementation and hydration strategies were implemented to optimise ammonia excretion and prevent urinary stone recurrence. Regular monitoring confirmed clinical stability, with weight gain, improved coat quality and the resolution of urinary abnormalities up to 5 months following the prescribed diet. This case highlights the importance of individualised dietary management in congenital portosystemic shunts, emphasising the role of protein quality, micronutrient balance and hydration in mitigating metabolic complications and improving long‐term patient outcomes.