Portosystemic Shunt (PSS, Hepatic Shunt, Liver Shunt) in Dogs

Overview of Canine Portosystemic Shunt (PSS, Hepatic Shunt)

A portosystemic shunt, commonly abbreviated and referred to as PSS, hepatic shunt or liver shunt, is an abnormal communication between blood vessels, which causes blood to bypass the liver that can occur in dogs. The portal vein is a major vessel in the body which enters the liver and allows toxic components of the blood to be detoxified by the liver. When a shunt is present, the portal vein, or one of its related veins, is inappropriately connected to another vein which creates blood flow around the liver.

The most common type of shunt is a single congenital shunt. This means that the dog or other animal is born with the problem. Acquired shunts may occur secondary to liver disease.

Congenital shunts occur in both dogs and cats. Most animals start showing signs by six months of age. However, shunts have been diagnosed in adults as old as 10 years.

Shunts are more common in purebred dogs than mixed breeds. The breeds predisposed to congenital shunts include: miniature schnauzer, Yorkshire terrier, Irish wolfhound, cairn terrier, Maltese, Australian cattle dog, golden retriever, Labrador retriever, and Old English sheepdog.

It occurs more often in female dogs, and of the affected males, there is also an increased incidence of cryptorchidism, in which one or both testicles remain undescended.

The impact of a portosystemic shunt on your pet can present itself in a variety of ways. The most common clinical signs are a result of elevated toxin levels in the blood secondary to failure of removal by the liver. One of the important toxins is ammonia, which causes abnormalities of the central nervous system.

What to Watch For

Diagnosis of Portosystemic Shunt (PSS) in Dogs

Treatment for Portosystemic Shunt (PSS) in Dogs

Home Care and Prevention of Liver Shunts in Dogs

Give all medications as prescribed by your veterinarian. Feed only the prescribed diet. Monitor your pet for recurrence or worsening of the original clinical signs that alerted you to a problem.

As this is a congenital disorder, there are no known preventative measures for your individual pet. However, any cat or dog with a shunt should never be used for breeding purposes.

Information In-depth for Portosystemic Shunt in Dogs

A congenital portosystemic shunt is a condition that exists when your pet is born. This is a serious disorder because the liver does not receive adequate blood flow, and therefore does not grow normally. Most animals with shunts have livers that are smaller than normal. Because of the inadequate blood flow and improper growth, the liver does not function properly.

The liver is an enormously important organ that has many functions. The most notable abnormalities that result from a shunt are those affecting:

Although the CNS problems are the most common, some pets show only urinary tract or gastrointestinal signs. Some animals may show a failure to grow normally as the only obvious abnormality. Because the clinical signs can be quite varied, there are a number of other conditions that can cause similar signs, including:

Diagnosis In-depth of Portosystemic Shunt in Dogs

Treatment In-depth of Portosystemic Shunt in Dogs

Surgical ligation of the shunt is the preferred treatment. However, animals may need to be medically stabilized before they are good candidates for anesthesia and surgery. In some cases it may not be possible to close the shunting vessel completely; this depends on its location. This is most often a problem in large breed dogs. If surgery is not an option, medical management is the mainstay of therapy. Medical treatment may include:

Follow-up Care for Dogs with Portosystemic Shunt

Optimal treatment for your dog requires a combination of home and professional veterinary care. Follow-up can be critical, especially if your dog does not rapidly improve.