Portosystemic shunts are abnormal blood vessel connections that bypass the liver in dogs, causing toxin accumulation and neurological signs that can be managed medically or corrected surgically.
Portosystemic shunts create welfare suffering from earliest life: affected puppies may fail to thrive, experience disorientation and neurological episodes (hepatic encephalopathy), and suffer hypoglycaemic episodes that are frightening and potentially fatal. The neurological signs - confusion, aimless wandering, pressing the head against walls - indicate significant brain dysfunction from ammonia and toxin accumulation that is distressing to experience and observe. Diagnosis is often delayed because symptoms are intermittent and nonspecific. Surgical correction, when possible, offers the prospect of normal or near-normal life, but the procedures are technically demanding and expensive. Medical management alone provides acceptable quality of life in some dogs but requires very strict dietary control and lifelong monitoring. Breed predisposition represents a preventable welfare burden - breeding programs should screen for and reduce PSS prevalence.