Portosystemic Shunts

What is a Portosystemic Shunt?

Portosystemic shunting is a vascular abnormality whereby blood circulation from the intestines by-passes the liver. Nutrients and toxins absorbed from the intestines that are normally processed by the liver enter directly into systemic circulation, which can cause a variety of signs including poor-growth, abnormal behaviour (particularly after meals), increased thirst, and abnormal urination patterns. While multiple portosystemic shunts can be acquired as the result of a very diseased liver (such as chronic hepatitis), shunting through a single aberrant vessel is always a congenital abnormality. Certain breeds, such as the Yorkshire terrier, are predisposed to this condition; however, dogs and cats of any breed and size can be affected.

Advanced Diagnostics for Portosystemic Shunts

Portosystemic shunts are one of the most common congenital abnormalities seen by our soft-tissue surgery service. The UFVH offers the advanced diagnostics required to detect and characterize the abnormal vessel, including Doppler ultrasound, nuclear scintigraphy, and mesenteric portography. We are also fortunate to be able to offer computed tomographic (CT) angiography, a non-invasive, highly sophisticated imaging technique that enables our surgeons to gain a detailed understanding of the vascular anatomy within the abdomen prior to surgery.

What does the treament involve?

Surgery is the ideal treatment if we suspect your pet has a single congenital portosystemic shunt. The procedures are performed by our board-certified surgeons, as correct identification and isolation of the abnormal vessel can be difficult. Our surgeons have an array of methods to slowly close the offending vessel, including placement of ameroid constrictors, cellophane banding, and hydraulic occluders.

Shunts that enter the systemic circulation from within the liver itself are called intrahepatic shunts. They are often difficult to identify in surgery, hence often require more detailed pre-operative planning (such as CT angiography). Collaboratively with our Cardiology and Radiology services, we are one of few North American institutions that can also offer minimally invasive interventional therapy. This involves placement of expandible metallic stents and coils via a peripheral vein to attenuate intrahepatic shunts, which means your pet avoids the morbidity associated with open-abdominal surgery and likely shorter stay in hospital.

Post Operative Care

While complication rates are low, your pet will require close monitoring and supportive care in our intensive care unit for 2-3 days post-operatively, even when surgery is short and uneventful. Patients are carefully monitored by our specialized ICU staff 24 hours a day.