Portosystemic Shunts (PSS) And Portal Vein Hypoplasia (PVH)

Question 1

The _______ ____ receives blood from pancreas, small and large intestines, spleen, and stomach

Answer 1

Portal Vein

Question 2

What is the cycle of ammonia detoxification?

Answer 2

Ammonia - produced in GI tract —> portal circulation —> liver —> urea cycle: ammonia —> urea —> urea excreted by kidneys

Question 3

What is a portosystemic shunt and what results from it?

Answer 3

• It is an anomalous vessel that bypasses the liver
• It decreases delivery of trophic factors (primary insulin and glucagon) to liver
• It decreases clearance of toxins

Question 4

A portosystemic shunt leads to hepatic encephalopathy, how does it do this?

Answer 4

Ammonia bypasses liver —> systemic circulation —> brain

Question 5

What are some clinical signs of hepatic encephalopathy?

Answer 5

Ataxia, weakness, stupor, head pressing, circling, star gazing

Question 6

What are some precipitating factors of hepatic encephalopathy?

Answer 6

• High protein meal
• GI hemorrhage
• Constipation
• Hypokalemia
• Alkalosis

Question 7

What are two types of extra hepatic shunts?

Answer 7

Congenital and Acquired

Question 8

What are the types of intrahepatic shunts?

Answer 8

There is only a congenital

Question 9

This is described as microscopic intrahepatic shunt in older dogs

Answer 9

Portal vein hypoplasia (aka microvascular dysplasia)

Question 10

How do you diagnose PSS?

Answer 10

Non-invasive imaging (AUS, nuclear imaging, CT or MRI), protein C activity, invasive imaging (portovenography)

Question 11

How do you medically treat PSS?

Answer 11

• Decrease signs of HE by giving Lactulose
• Decrease number of ammonia-producing bacteria (ABX, enemas)
• Decrease substrate for NH3 production (low protein diet and control GI hemorrhage)

Question 12

What surgical intervention can you do to treat PSS?

Answer 12

Ameroid constrictor or cellophane banding