A liver shunt is a condition where an abnormal blood vessel develops that bypasses the liver. This prevents the blood from being filtered of toxins before it is passed on to other organs, including the heart. Yorkshire terriers, Irish wolfhounds, Labrador retrievers and toy breeds are dog types that liver shunts are common in.
-
Congenital Shunts
-
While in the womb, a shunt called the "ductus venosus" carries blood through the liver to the heart. As a fetus, a puppy's liver does not work. Right before or after birth, the puppy's liver will begin to work and the ductus venosus will stop transferring the blood through the liver. Unfortunately, sometimes the shunt does not shut down and continues to function. When this happens, the condition is called an intrahepatic shunt. Another congenital shunt is the extrahepatic shunt. This is where a blood vessel develops on the outside of the liver. This abnormal vessel remains open after the ductus venosus closes carrying blood to other organs throughout the body without being filtered by the liver first.
Symptoms
-
Symptoms usually start to show when the dog is a puppy. Liver shunts affect the central nervous and gastrointestinal systems. Because the central nervous system is affected the puppy may behave oddly by walking in circles or staring into space. Also the dog can start to have seizures. The effects on the gastrointestinal system can vary. The dog may gain too much weight too quickly or lose weight too quickly. He may experience vomiting and diarrhea. Occasionally, a dog will show no symptoms of liver shunt disease until it gets older as bladder and kidney infections and stones develop.
Diagnosis
-
A veterinarian will order blood tests that will check the protein, ammonia and bile acid levels. X-rays of the abdomen can show if the liver is underdeveloped. A contrast X-ray called a portogram can show the actual shunt. One other method of diagnosis is by ultrasound.
Treatment
-
Dogs with liver shunts will be put on a low-protein diet. A veterinarian may prescribe medication like lactulose and metronisazole to keep ammonia and other toxins from being absorbed into the body. While some dogs can live on medication alone, most dogs' livers will continue to shrink and will need surgery. The veterinarian will partially close the shunt and restore blood flow through the liver. Another surgery that is possible is the placement of an ameroid constrictor. This device is placed around the shunt. Over a four- to five-week period, the ring constricts the blood flow and allows the liver time to get used to functioning again.
Prognosis after Ameriod Surgery
-
According to Pure Silk Kennels, the survival rate is over 95 percent for dogs that have an ameroid constrictor placed. Only about 15 percent of dogs will continue to have problems after the surgery. Normally the underdevelopment of the blood vessels in the liver is the reason for continued problems. Dogs who continue to have problems will have to stay on a low-protein diet and take medication for the rest of their lives.
-