Portosystemic (Liver) Shunts in Dogs
Portosystemic shunts (PSS), also known as liver shunts or portosystemic vascular anomalies, are anatomical defects where one or more veins let blood bypass a dog’s liver. These veins are remnants of embryonic blood vessels that are supposed to regress shortly after a puppy is born. What causes portosystemic shunts is unknown. They may be caused by some insult to fetuses inside the womb. There almost certainly is a strong genetic component. As the abnormal veins shunt blood around the liver, substances that normally would be filtered, metabolized or modified by the liver stay in circulation. Many of these, especially ammonia, are harmful - especially to nervous system tissue. Affected dogs usually develop symptoms by 1 year of age. The signs of PSSs are nonspecific and episodic. They include lethargy, weakness, disorientation, drooling, vocalization, vision disturbances, pacing, stunted growth, vomiting, diarrhea, constipation, appetite changes, changes in urination, itchy skin, tremors, seizures and collapse.
Congenital portosystemic shunts (PSS) are embryonic blood vessels that do not regress normally before or just after birth. These veins “shunt” blood from the gastrointestinal tract and spleen around the liver, which causes toxins, nutrients and other substances that normally would be filtered, metabolized or modified by the liver to remain in circulation. Many of these substances, especially ammonia, are highly toxic to other tissues, especially to the central nervous system. The severe neurological symptoms
It is hard to speculate as to how dogs with congenital portosystemic shunts “feel” differently than they would have if they were not born with this anatomical abnormality. However, the primary effects that we see in dogs with this condition are largely neurological, gastrointestinal and/or urological in nature. Neurological means pertaining to the brain and central nervous system; gastrointestinal means pertaining to the digestive tract (stomach and small and large intestines); and urological refers to
Congenital portosystemic shunts (PSS) are usually diagnosed in young dogs (under 2 years of age) as a result of a combination of nonspecific symptoms. The results of a urinalysis and routine blood work (a complete blood count and a serum biochemistry profile) are typically unremarkable in dogs with portosystemic shunts, although there may be an elevation in liver enzymes, and some changes in blood urea nitrogen (BUN) levels. Abdominal radiographs (X-rays of the belly) may
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.