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Liver Shunt in Dogs

Posted January 22, 2015 in Dog Diseases & Conditions A-Z

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Dr. Phil Zeltzman is a traveling, board-certified surgeon in Allentown, PA. His website is He is the co-author of “Walk a Hound, Lose a Pound” (

Kelly Serfas, a Certified Veterinary Technician in Bethlehem, PA, contributed to this article.

One of the many jobs of the liver is to filter toxins carried by blood vessels that drain the intestine, among other organs. The toxins are processed by the liver, which is supposed to release only harmless substances to be used by the body.

In the mother’s womb, a puppy’s liver isn’t actually functional. The mother’s liver does all of the work. Toward the end of the pregnancy, a blood vessel is supposed to close down to allow the pup’s liver to take over the workload. If this change does not occur, a liver "shunt" is created. In other words, the abnormal vessel “shunts” or bypasses the circulation around the liver, which means that toxins are not processed and they continue on to the general circulation. From there, all kinds of health problems follow during puppyhood.

What health problems does a liver shunt cause?
Puppies may have a small size (due to stunted growth), poor muscle development and/or blindness. Affected puppies also can have neurological signs such as disorientation, walking in circles and even seizures. Other symptoms may include vomiting, diarrhea, a swollen belly, increased drinking and urination. Occasionally, dogs can have bladder stones. Signs are typically worse after a meal, when toxins from the intestine are at their highest levels.

Other types of liver shunts
In addition to the standard shunt (outside the liver [extra-hepatic shunt]), there are 3 rare and sometimes hard to differentiate conditions you should be aware of:

  1. A shunt inside the liver (intra-hepatic shunt). Surgery to correct this type of shunt is much more difficult and requires a very talented and experienced board-certified surgeon.
  2. Multiple shunts. This is a situation where there are dozens and dozens of small shunts outside of the liver. Unfortunately, surgery is not an option.
  3. Microvascular liver dysplasia. Here, there are hundreds or thousands of microscopic shunts inside the liver. Even though surgery is not an option to fix them, a liver biopsy is necessary to confirm the suspicion.

What breeds are at the greatest risk of a liver shunt?
Breeds affected by a shunt outside the liver tend to be small:

Larger dog breeds tend to have a shunt inside the liver more commonly:

A shunt is considered hereditary, so affected dogs should be spayed or neutered. Click here to learn more about the benefits of spaying or neutering your dog.

Related symptoms: 

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Dr. Phil Zeltzman is a board-certified veterinary surgeon and author. His traveling practice takes him all over Eastern Pennsylvania and Western New Jersey. You can visit his website at, and follow him at