A problem can occur where the blood flowing to and through the liver has a problem. There are several variations on this problem blood flow. In this page we will be correcting the blood flowing from a blood vessel that is directing the blood away from the liver and not into the liver like it should. This is called a liver shunt, also known as a porto systemic shunt (PSS).

This page shows a surgery to correct an extra-hepatic PSS (porto systemic shunt) in a cat using an ameroid ring. More than one year after surgery this cat is doing fine, so the surgery was a major success.

Graphic Photos to Follow

Diagnosis of a Liver Shunt

This shunt occurred in a cat, a rare situation since it mostly occurs in dogs. This cat had a strange behavior, a fever, and blood in its urine at an early age. The first hospital the owner went to thought it was FIP.

Our doctors did not think this was the case, and ran a blood panel as a start.

Liver Shunt Blood Panel Results

The elevated liver enzymes and the low BUN are an indication there is a significant problem with the liver

Liver Shunt Urinalysis Results

The urinalysis showed a large amount of Ammonium Urate Crystals, a significant abnormality that is seen in liver shunts

Elevated Bile Acids Test Results

A liver function test, called a Bile Acids Test, confirmed a serious problem with the liver. Normal is less than 13, this cat was over 135.

Ultrasound Picture of a Liver Shunt

Based on the above information an ultrasound was performed and a liver shunt was found. See reports below.

Liver Shunt Ultrasound Findings

The finding of a liver shunt is circled in these ultrasound findings

Liver Shunt Ultrasound Conclusion

The final report showed the possibility of an intrahepatic shunt, but further testing was needed to confirm this finding. Scintigraphy was recommended, and the report from that test is below.

Scintigraphy Report in a Cat with a Liver Shunt

Scintigraphy confirmed there was a shunt, but found out that it was extrahepatic. This is better news because now surgery can be performed. Surgery cannot be performed to correct the problem if the shunt is intrahepatic. 

Medical therapy consisting of flagyl, clavamox, lactulose, and a food called L/D made by Hill’s was instituted. It worked well and the symptoms of behavior changes and blood in the urine resolved. After many months of therapy it was decided that it was time do perform surgery to correct the problem.

Staff Picture with CatOur patient with our staff giving a “well wish” on the day prior to surgery

 You can learn more about how we diagnosed and treated this problem before surgery on our Liver Diseases Page.

Graphic surgery photos on this page.

Dr. Adam Gassel of the Southern California Veterinary Specialty Hospital performed the surgery. This surgery is not performed by any veterinary surgeon. Dr. Gassel has the special training, expertise, and experience to perform this delicate procedure, having trained with Dr. Tobias at the University of Tennessee College of Veterinary Medicine.

Aftercare is just as important as surgery in correcting this problem surgically, so this surgery needs to be performed at a 24 hour veterinary hospital where the staff is trained in this care.


A special constricting device called the Ameroid Ring is used to occlude the problem blood vessel to the liver

The ameroid ring is made of casein (a type of protein) that is surrounded by a ring of stainless steel. Over 4-5 weeks the normal fluid in the abdomen causes the casein to swell. Since it is encased in metal, the swelling slowly occludes the blood vessel with abnormal blood flow to the liver.

It is important that the casein swells slowly to allow the liver to adjust to the new pressure within it from the other blood vessels that are now increasing their blood flow to the liver. If the problem blood vessel decreases its flow to the liver too fast there can be serious consequences and even liver failure.

This surgery is performed after a careful review of all data and a discussion with the owner of the possible complications due to surgery. Cats tend to have more post operative complications compared to dogs, so special care is paid to their needs to help ensure a successful surgery.

PSS Surgery

Dr. P watched the surgery and took these photos to help explain this procedure.

Our friend is carefully prepared for surgery to minimize any chance of infection

While our patient is prepped Dr. Gassel is preparing his instruments


Our surgeon preparing to start the surgery while his anesthetist closely monitors our patient

The procedure does not start until our patient is under the proper plane of anesthesia and is stable

Our patient’s blood pressure is manually monitored throughout the procedure

Before making the initial skin incision Dr. Gassel confirms with his anesthetist that our patient is ready for surgery

The skin is incised gently to minimize trauma that could post operative discomfort and can delay healing

Small blood vessels are cauterized before proceeding further

The abdomen is entered at a special location in the muscle called the linea alba. This is where two tendons of the abdominal muscles come together. This area is stronger than muscle tissue, and will hold the final sutures when we put the muscle back together at the end of the procedure. This will prevent a hernia. 

As soon as the abdomen is entered the swollen and yellow discolored liver appears. You can see it between our surgeon’s fingers. The liver is this way because of the disease process going on. 

Finding and exposing the extra hepatic blood vessel for correction amidst all of the blood vessels, fat, and tissue in the area is tedious, and takes delicate dissection to get the vessel completely exposed for the Ameroid Ring to be placed. This is where Dr. Gassel’s expertise comes into play.

After much dissection you can see him starting to expose the vessel with his instrument. The extra hepatic blood vessel is the reddish horizontal object under the swollen and yellow-colored liver.

You can easily visualize the extra hepatic blood vessel over the hemostat as it is exposed carefully enough to put on the ring

The next important part of the procedure is picking the correct sized Ameroid Ring. If it is too big it won’t occlude the extra-hepatic vessel enough to help. If it is too small it will occlude the blood flow too rapidly and cause the liver to fail.

The ring is prepared by removing the locking pin

The extra hepatic blood vessel is very gently placed in the ring through the opening in the ring where the pin was

When Dr. Gassel feels the ring is the correct size the locking pin is placed back in


The final appearance of the Ameroid Ring before our patient’s linea alba and skin are sutured back and our patient is awakened

Dr. Gassel and his surgical assistant after a successful surgery

One of the ways we diagnose a PSS is with a bile acids test. After surgery the bile acids test should be back to normal. We are happy to say that after over one year our patient’s bile acids test is back to normal and he is feeling great!

This was the original bile acids test on this cat. It should be less than 13, and is over 135. To have it go from this, to perfectly normal, is a testimonial to the expertise of the surgical team at the Southern California Veterinary Specialty Hospital.

There is much more to liver shunts, which you can learn about on our Liver Diseases Page.

Return to Feline Diseases Page