A liver shunt is also known as a portosystemic shunt, portacaval shunt or portosystemic vascular anomaly. This abnormality occurs when a pet’s blood, returning from the intestinal tract, gets shunted past the liver.
In the normal pet, blood vessels pick up nutrients from ingested material in the intestine and carry it through the liver to be processed and detoxified. In the case of a shunt, an abnormal blood vessel carries this blood around the liver and dumps the nutrients directly into the general circulation. As a result, toxins build up in the bloodstream.
Pets can be born with the shunt (congenital) or can develop it later (acquired). Breeds that are more likely to have congenital shunts include Cairn Terriers, Yorkshire Terriers, Maltese, Irish Wolfhounds, Himalayans and Persians. An acquired shunt can develop in any breed and is usually caused by liver problems due to toxins, hepatitis, infections, inflammation, etc.
Symptoms of a liver shunt include stunted growth, weight loss, vomiting, diarrhea, lethargy, unresponsiveness, seizures, disorientation, poor skin and coat, excessive drinking and urination. Some pets will have a single sign and some will have several.
We diagnose shunts with a combination of blood tests, a urinalysis and imaging tests (radiographs and/or ultrasounds). A liver function test called bile acids is usually very suggestive for a liver shunt when the values are very high.
Therapy, and how well a pet responds to it, is dependent on many things–including the location and severity of the shunt. Some pets will do well for long periods of time with medical management only. Medical management includes a low protein diet, antibiotics and lactulose. Surgical repair is commonly done for congenital shunts and again the success is dependent on the location and severity of the shunt. The surgical procedure, unfortunately, is rarely successful in cats.