Portosystemic shunt (PSS) in Dogs , referred to as a liver shunt, is a medical condition in dogs that disrupts the normal flow of blood through the liver. Typically, blood from the intestine, spleen, and pancreas pass through the portal vein into the liver, where it is detoxified, supplied with essential nutrients, and regulated for sugar balance. However, in dogs with PSS, this critical blood flow is diverted away from the liver due to an abnormal connection known as a shunt.
This shunt forms between the portal vein (or one of its branches) and another vein, which causes the blood to bypass the liver and flow directly into general circulation. As a result, the liver is circumvented, preventing the necessary detoxification and nutrient regulation that is vital for the dog’s health.
PSS can lead to severe health complications in dogs if not promptly diagnosed and treated. Understanding the symptoms, causes, and available treatments is crucial for pet owners who want to safeguard their dogs’ well-being.
Symptoms of Portosystemic Shunt (PSS) in Dogs
The symptoms of PSS can vary depending on the severity and type of shunt. Some dogs might show only mild symptoms, while others could present with severe clinical signs. Here are some key symptoms include:
- Poor growth or stunted growth in puppies
- Disorientation or confusion
- Weakness or lethargy
- Increased thirst and urination
- Vomiting
- Diarrhea
- Loss of appetite
- Weight loss
- Salivation
- Seizures or unusual neurological symptoms, including aggressive behavior, blindness, or circling
These symptoms often become more noticeable or worsen after eating, as the ingestion of food leads to an influx of toxins entering the bloodstream from the digestive tract. It’s important to consult a veterinarian if your dog displays any combination of these symptoms, as they can also be indicative of other serious health conditions.
Causes of Portosystemic Shunt (PSS) in Dogs

There are two primary types of portosystemic shunts in dogs: They are congenital and acquired.
Congenital Shunts: These are present at birth. It occurs as a result of genetic factors, making certain breeds more susceptible. There are two categories of Congenital shunts such as intrahepatic and extrahepatic shunts. Intrahepatic shunts occur within the liver. Large dog breeds are susceptible to this typical shunt. However smaller breeds are vulnerable to extrahepatic shunts. It affects outside the liver.
Breeds that are at a higher risk for congenital PSS include:
- Irish Wolfhound
- Italian Greyhound
- Old English Sheepdog
- Golden Retriever
- Labrador Retriever
- Bernese Mountain Dog
- Cairn Terrier
- Yorkshire Terrier
- Yorkipoo
Acquired Shunts: These develop later in a dog’s life, often as a secondary consequence of liver diseases such as cirrhosis. In these cases, as the pressure increases in the portal vein blood reroutes around the liver. While acquired shunts can occur in any breed, they are more commonly seen in older dogs.
Diagnosing PSS in Dogs
Diagnosing PSS can be challenging due to the vagueness of the symptoms, which can mimic other conditions. You have to thoroughly investigate into changes of your dog.
- Bloodwork: A complete blood count (CBC) and a serum chemistry panel help evaluate liver function and assess levels of various substances in the blood.
- Urinalysis: This test can identify abnormalities in the urine, such as high levels of protein or blood, which might indicate liver dysfunction.
- Imaging: Ultrasounds or CT scans are recommended to detect any abnormalities in the liver and blood vessels.
- Additional Testing: If PSS is suspected, a bile acids test or a shunt study may be conducted to confirm the diagnosis.
Treatments for Portosystemic Shunt (PSS) in Dogs

Treatment for PSS depends on the severity of the condition and whether the shunt is congenital or acquired.
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Surgical Treatment: The most precise and clear treatment for congenital PSS is surgical ligation or gradual closure of the abnormal vessel. The surgery aims to redirect blood flow through the liver, enabling proper metabolism and detoxification. While this surgery can have a high success rate, its success depends on various factors, including the dog’s overall health and the complexity of the liver shunt.
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Medical Management: In cases where surgery is not an option, or as a supplementary measure before or after surgery, a medical approach may be recommended. This involves a special diet that is lower in proteins to ease the burden on the liver on your dog. Additionally, medications like lactulose, which reduces ammonia absorption from the gut, and antibiotics to decrease ammonia production by gut bacteria, may be prescribed. In fact, medical management can alleviate symptoms but does not cure PSS. It is particularly valuable for dogs that are not suitable candidates for surgery.
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Interventional Radiology: For some dogs, interventional radiology may be an option. This technique uses imaging guidance to place coils or other devices that gradually close the shunt internally. This method often carries fewer risks than traditional surgery and usually allows for a quicker recovery. However, it is not suitable for all types of shunts and is not existing in all veterinary practices.
Long-term Management and Follow-up
Regardless of the treatment chosen, long-term management of PSS is often necessary. Direct your dog to regular veterinary check-ups that are essential to monitor the dog’s condition and adjust treatments as needed. In some cases, dogs may require ongoing medication for the rest of their lives to manage symptoms and prevent complications. If needed, you may change their dietary needs and lifestyle as recommended by the vet to support liver function and overall health of your dog.
If you are vigilant about your dog’s symptoms and seeking timely veterinary care, you can help manage PSS and improve your dog’s quality of life.