Dear Daisy Dog
Our Yorkshire terrier puppy was just diagnosed with a liver shunt, for which our veterinarian recommends surgery. Would you explain this disease?
A puppy born with the shunt you refer to, a portosystemic shunt (PSS), has an abnormal blood vessel pathway in the abdomen, allowing blood to bypass the liver.
To help you understand this abnormality, let me start by explaining how things work in a normal dog like me.
The protein I eat is digested to form ammonia, which is absorbed by the blood vessels around my intestines and carried by the portal vein to my liver.
Ammonia is toxic, especially to the brain, so the liver detoxifies it and releases it into the general “systemic” circulation as urea.
Your pup’s PSS shortcuts this process. The shunt connects the portal vein directly to the systemic circulation, bypassing the liver.
Therefore, ammonia can reach the brain, where it may cause seizures or other signs of abnormal brain function, which are often worse after eating.
The shunt in a small-breed dog is usually a single blood vessel outside the liver, so the treatment of choice is to tie off the shunt vessel.
If surgery is not possible, diet and medications can help.
PSS dogs eat a low-protein diet composed of eggs and cottage cheese with plenty of carbohydrates, or a specially formulated prescription diet. Medications such as lactulose help reduce the production of ammonia.