Liver Shunt in Dogs

Yorkie on an exam table at the veterinary hospital.

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Liver shunts can go unnoticed in a dog but they can cause serious issues if left unmanaged or untreated. Serious liver shunts can cause severe problems, so it is beneficial for a dog owner to understand what a liver shunt is and how to recognize the signs of one. This can help prevent serious complications and harm to a dog with this internal problem.

What Are Liver Shunts in Dogs?

Congenital portosystemic shunts are commonly referred to as liver shunts and are problems with the blood vessels that are supposed to run into the liver. Normally, blood vessels transport blood through the liver so that the liver can filter the blood to remove toxins, medications, and wastes from the body alongside absorbing nutrients from the food. If the blood vessels bypass the liver then these things do not occur. This leaves the toxins and waste to enter the body and nutrients to not be properly absorbed. Some dogs have multiple shunts while others only have one and dogs can also have intrahepatic (inside the liver) or extrahepatic (outside the liver) shunts.

Signs of Liver Shunts in Dogs

  • Abnormally small in size
  • Staring at walls
  • Ataxia/stumbling
  • Seizures
  • Excessive urination
  • Circling
  • Head pressing
  • Vomiting
  • Diarrhea
  • Excessive thirst

The most common sign that a dog has a liver shunt is stunted growth. Runts of the litter are often diagnosed with liver shunts since this problem causes issues with nutrient break down from food. These small puppies may also be quieter or more reserved than their counterparts due to the issues with energy regulation.

Chronic liver shunts or severe cases may cause a dog to head press, stare at walls and doors, stumble around as though it is drunk, circle, and even have seizures. These scary symptoms are usually more obvious to a dog owner than simply being a small and quiet puppy.

Occasionally vomiting and diarrhea may occur in dogs with liver shunts and if the kidneys and bladder is affected from a buildup of toxins in the body, excessive thirst and urination may also be seen.

Causes of Liver Shunts in Dogs

Congenital portosystemic shunts are present at birth and are a result of one of two things that happened in the body.

  • Ductus venosus stays open: The ductus venosus from the placenta that bypasses the liver stays open and intact even after the developing fetus no longer needs it in utero.
  • Abnormal blood vessel development: An abnormal blood vessel develops in the body that stays open after the ductus venosus closes in utero.

One other type of liver shunt can occur in dogs due to severe liver disease but this is not present at birth and is called an acquired portosystemic shunt. This type of shunt is not seen in puppies but rather in older dogs that have been battling liver issues.

Breeds At Risk for Developing a Liver Shunt

There is no genetic test for portosystemic shunts in dogs but many breeds are commonly affected and include:

Diagnosing Liver Shunts in Dogs

After a full physical examination, your veterinarian will run some blood tests to check the health of the liver and blood. A complete blood count, liver enzyme analysis, and a bile acid test are the starting points for diagnosing a shunt. A urinalysis is also regularly performed in order to assess the health of the the bladder, urine, and kidneys. Sometimes further diagnostic testing is recommended and may include an ultrasound, X-rays, CT scans, an MRI, or even surgery to visualize the liver and blood vessels.

Treatment of Liver Shunts in Dogs

Surgery is often needed to correct and close the shunt. This type of surgery is usually very successful in dogs with only one extrahepatic shunt but multiple shunts or intrahepatic shunts may be present in some dogs which may not make surgery a curative option.

If surgery is not an option financially, a dog has multiple shunts, or the shunts are intrahepatic then medications and diet may help to manage the symptoms. Special diets that are low in protein and medications to help a dog tolerate protein are often used since dogs with liver shunts cannot metabolize it well. The source of protein alongside the amount a dog with a liver shunt consumes can vary from dog to dog so a veterinary nutritionist may be involved in creating the ideal treatment plan for your specific dog.

If neurological symptoms, such as circling, head pressing, and seizures, are present, this is usually due to the protein waste that isn't excreted from the body due to the liver shunt. Medications may help ameliorate these symptoms but in extreme cases, euthanasia is elected if symptoms are not able to be managed.