Portosystemic (Liver) Shunts in Dogs
Introduction
Portosystemic Shunts in Dogs: Veterinary reviewed information that provides a detailed explanation of Portosystemic Shunts in dogs. Get started and see what choices you and your vet can make to manage Portosystemic Shunts in Dogs.
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Definition
A portosystemic shunt (PSS), also often called a liver shunt or a portosystemic vascular anomaly, is essentially a defect in which one or more abnormal veins allow blood from the intestines and elsewhere in systemic circulation to circumvent the liver. These veins are actually remnants of normal embryonic blood vessels that for some reason fail to regress normally after the puppy is born. Portosystemic shunts may be congenital (present at birth) or acquired after birth. Congenital portosystemic shunts, which are the most common form of this disorder, typically are evident by the time a puppy reaches 6 months of age; in almost all cases, clinical signs will be obvious to owners before the dog reaches two years of age.
Congenital portosystemic shunts usually involve a single large fetal blood vessel in or close to the liver. When the vein is inside the liver, it is called an “intrahepatic” shunt; when the vein is outside of the liver, it is called an “extrahepatic” shunt. “Hepatic” means pertaining to the liver. Intrahepatic portosystemic shunts are more common in large breed dogs and are more difficult to correct surgically. Extrahepatic portosystemic shunts are more common in small dogs and are more easily corrected. When a portosystemic shunt exists, the blood from normal systemic circulation bypasses the liver. Because the liver is involved in so many essential bodily functions, including detoxification of noxious substances from the blood and the synthesis and breakdown of fats, portosystemic shunts cause a potpourri of problems for affected dogs.
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.