Portosystemic Shunts in Cats

The portosystemic shunt (PSS) is an abnormal communicating vessel between the portal and systemic vasculature. The liver is underdeveloped due to decreased blood flow. The PSS may be congenital (intrahepatic or congenital) or acquired (extrahepatic). Ammonia and intestinal toxins are not cleared in the liver, causing various clinical signs of hepatic encephalopathy. Medical treatment is aimed at minimising clinical signs and stabilising the cat prior to surgical treatment. Surgical treatment is currently the method of choice; however, the best method of occluding the shunts has yet to be found. Surgical treatment involves complete ligation of the shunt in cases where the portal vasculature is adequately developed, but more commonly the surgery aims to occlude the shunt gradually with a cellophane banding or ameroid ring. The cellophane may not produce the same fibrotic response as in dogs, so clinical signs often improve, but the cat still requires medication. In general, the prognosis after surgery in cats is not as good as in dogs. Keywords: Portosystemic shunt; Cats; Neurological signs; Seizures, Cellophane banding