Liver Shunts in Dogs

The portal vein is an important blood vessel which normally enters the liver and allows toxic elements in the blood to go through the normal detoxification process. When your dog has a liver shunt, the portal vein is not properly connected, and therefore, blood normally detoxified by the liver will bypass it and go directly back into circulation throughout the body. Additionally, the liver will often have poor development.

A congenital shunt is the most common liver shunt. A liver shunt acquired outside of genetics is usually seen as a secondary problem of the liver. A congenital shunt can present two ways; an extrahepatic shunt is found outside of the liver and is mostly seen in small breeds, while an intrahepatic one is found within the liver and is typically found in large breeds. 

A liver shunt is known medically as a portosystemic shunt, hepatic shunt, or PSS. 

Growing dogs with liver shunts may exhibit stunted growth. Dogs may also show signs of gastrointestinal distress, urinary issues, and unusual behaviors. Clinical symptoms of a liver shunt can include:

• Loss of appetite
  
• Vomiting
• Diarrhea
• Constipation
  
• Stumbling
  
• Circling or pacing
  
• Head Pressing
• Changes in behavior
• Staring excessively
• Anorexia
• Disorientation
  
• Lethargy
  
• Frequent urination
• Straining while urinating
• Blood in the urine
• Weight loss
• Stunted growth
• Seizures
  
• Blindness
  

Types

There are two types of liver shunts.

• Extrahepatic shunt outside of the liver
• Intrahepatic shunt inside the liver

A liver shunt can either be present at birth, or develop as a result of another medical condition of the liver. Causes include:

• Congenital shunt caused by a genetic predisposition before birth
• Acquired shunt caused by a complication due to progressive liver failure, or other liver problem

A congenital shunt is most common in certain predisposed breeds, including:

• Yorkshire Terrier
• Cairn Terrier
• Miniature Schnauzer
• Golden Retriever
• Labrador Retriever
• Australian Cattle Dog
• Irish Wolfhound
• Maltese 
• Old English Sheepdog

Once your veterinarian has determined that your dog has a liver stunt, treatment can begin. For some dogs, a surgical procedure called a portosystemic shunt ligation can help by totally or partially cutting off the shunt to encourage blood flow back into the liver for detoxification. This procedure does require your dog take anesthesia. 

Due to the risk of anesthesia to dogs with a liver shunt, health stability is essential before surgery can begin. To balance the levels of electrolytes and restore your dog’s hydration, IV fluid therapy may be administered. Levels of ammonia should be lowered and toxins absorbed in the intestine using lactulose. Antibiotics could also be administered to reduce the level of ammonia and bacterial overgrowth. For dogs showing signs of diarrhea and vomiting, your veterinarian also may order gastric protection medication. 

Not all dogs will require surgery, or can safely undergo the procedure, and may be treated with a diet change and medication. 

Surgery to repair a liver shunt is generally successful, with 85% of dogs experiencing complete recovery. Another 10% may have recurrent symptoms and may need more care. A small percentage of dogs can experience severe symptoms after surgery that can lead to death.

Once your dog has been released, keep an eye on any complications that may occur, such as abdominal swelling. You may need to clean and redress the incision site, and feed your dog a new or specialized diet. If the liver shunt was caused by a liver condition, your veterinarian will direct you on how to treat and manage the original condition.

Your dog will need regular liver evaluation and check-ups throughout the rest of their life to ensure they stay healthy. Dietary therapy as prescribed by your veterinarian is often prescribed, as well as continued lactulose administration.