What is a portosystemic shunt?
A portosystemic shunt is a condition in which blood bypasses your dog’s liver. Normally, a blood vessel called the portal vein is attached to your dog’s liver, but, with this condition, the portal vein is incorrectly connected to another part of your dog’s body. Because the liver helps to clean blood by filtering out toxins, when the blood bypasses the liver, the unclean blood gets distributed to other organs in your dog’s body including the heart and brain. In addition, because the liver is not being supplied with enough blood, the liver is unable to thrive and function properly which impacts your dog’s ability to digest and metabolize food. 

A portosystemic shunt may occur inside the liver (intrahepati) cor outside the liver (extrahepatic).

What will a portosystemic shunt look like in my dog?
Your dog will likely seem weak, have a decreased appetite, vomiting or diarrhea (sometimes bloody). Your dog may also have seizures, pace or loss of vision. Symptoms will generally worsen shortly after your dog eats. In addition, because the condition will impede your dog’s ability to digest and metabolize food, your dog may appear skinny or stunted.

Dogs with this condition frequently develop a specific urinary stone called a urate stone. A good portion of dogs with  porto-systemic shunt are first brought to the vet because they are suffering from urinary stones. Hypoglycemia (low blood sugar) and elevated ammonia levels which may cause seizures are also associated with this condition.

How does my dog get a portosystemic shunt?
This is a congenital condition meaning it is present at birth.

How is a portosystemic shunt diagnosed?
Your veterinarian will perform blood work and a biochemical profile to asses liver health. Your vet will also likely analyze your dog’s bile acid as this provides valuable information about liver function. Sometimes your vet may also be able to see the shunt itself by using a diagnostic imaging technique such as ultrasound.

How is a portosystemic shunt treated?
Surgery or medical management are the two options for treating this problem. Surgery is usually the best treatment option and, in most cases, surgery will be successful. A special diet, such as a low-protein diet, is also often recommended before and after surgery.

Surgical correction of  this condition is usually performed by placing an ameroid constrictor (a device used to occlude blood flow) around the vessel that is diverting the blood away from the liver so blood flow can redirect toward the liver. This procedure is done both for both extrahepatic and intrahepatic shunts. Intrahepatic liver shunts are generally a bit more difficult to repair.

The medical regime is usually centered around lowering the protein in the dog’s diet (often Hill’s L/D food is given) along with lowering the ammonia levels in the blood. Medicines such as metronidazole and lactulose are used also to help with this process. However, a very small percentage of dogs can be helped by medical management. Studies have demonstrated that greater than 50% of the dogs for whom medical management is chosen will be euthanized approximately 10 months from when the condition is found. Surgery is thus, most often, the best option.

How is a portosystemic shunt prevented?
You should not breed a dog with a portosystemic shunt, nor should you get a dog with a family history of this condition.

Can I get a portosystemic shunt from my dog?
No, you cannot contract this condition from your dog.