The main goal of treating a dog with a congenital portosystemic shunt (PSS) is to reverse the neurological signs of hepatic encephalopathy by eliminating the shunting of blood around the liver. Other goals are to relieve the gastrointestinal and urological signs associated with the condition. Congenital portosystemic shunts are typically treated surgically. Before surgery, the dog will be given inpatient supportive care, including nutritional and fluid management, to optimize the success of the surgical procedure. The veterinarian will attempt to occlude or ligate (tie off) all or part of the anomalous vessels that are re-routing blood around the liver, so as to restore normal or near normal blood circulation and liver function. Complete ligation may not be possible, but even with partial ligation the dog may be able to live a happy and full life without further treatment.
However, owners should recognize that when the abnormal vessel is occluded, the blood pressure through the liver may rise so much that it can cause seizures and, in very rare cases, even death. The hepatic (liver) vasculature initially may not be able to accommodate all of the blood that previously was shunted through the anomalous vein. Fortunately, even a partial ligation of the shunting vein resolves many of the dog’s symptoms and restores a fairly normal quality and duration of life in roughly 70% to 80% of dogs. Sometimes, however, postoperative complications do occur. These may include seizures, high portal blood pressure, sepsis, endotoxemia, hemorrhage, acute pancreatitis, bloody diarrhea, abdominal pain, elevated heart rate (tachycardia) of unknown origin, high or low body temperature (hyper- or hypothermia).
Good nutritional support is another component of a management protocol for dogs with liver shunts. Many veterinarians recommend a well-balanced, protein-restricted diet to help control the signs of hepatic encephalopathy which commonly accompany a PSS.
If the anomalous blood vessel can be completely ligated (tied off surgically), the dog’s prognosis is excellent. If only a partial ligation is accomplished, the prognosis ranges from good to poor. If surgery is not done and only medical management (drug therapy and supportive care) is attempted, the outlook is usually poor. Intrahepatic portosystemic shunts (those located within the liver itself) are much more difficult to correct surgically than are extrahepatic shunts, where the blood vessel is outside of the liver. The ultimate prognosis depends upon how well the remaining liver vasculature functions once the abnormal vessel is occluded. Owners should be aware of the risks of putting a dog with a PSS under general anesthesia; according to some experts, the surgical and anesthetic mortality rate ranges from 5% to 25%.