QUESTIONS

1. There are 5 types of congenital (single) shunts. Describe them & note the two most common.
    
2. Whatinthehellis a ductus venosus?
    
3. When we consider whether a young animal might have a liver shunt, one of the things we are concerned about is the development of neurologic signs after a high protein meal. How consistent a finding is this in liver shunt cases?
    
4. Something else to look for is a microcytosis of red cells. How consistent is this sign?
    
5. Will most liver shunt pups have an elevated alkaline phosphatase?
    
6. What would you expect cholesterol levels to be like in a shunt case?
    
7. List as many techniques as you can think of to diagnose PSS.
   
   
   
   
    

ANSWERS

1. The 5 types of single liver shunts are:
   
   a) Patent Ductus Venosus - 28% of cases in the dog
   
   b) Portal vein atresia with development of multiple collateral systemic communications (very rare)
   
   c) Drainage of the portal vein into the vena cava - 45% of cases in the dog (& especially popular w/the small breeds)
   
   d) drainage of the portal vein into the azygous vein
   
   e) drainage of the portal vein & postcava into the azygous vein with discontinuation of hte prerenal segment of the postcava
   
   
   
   
    
2. The ductus venosus is an embryonic channel of the umbilical vein.  It crosses the liver & drains into the left hepatic vein & then into the post cava.
   
   
   
   
    
3. According to Ettinger's book, neuro signs after a high protein meal occur in only 25% of shunt cases. (Note, in cats, drooling is a special sign to watch for. Sharon Center also notes that all her feline shunt cats seem to have copper colored eyes.)
   
   
   
   
    
4. 72% of cases have microcytosis.
   
   
   
   
    
5. Alkaline phosphatase will probably be elevated but not from the shunt. You will be seeing elevations due to the bone isozyme which is elevated in growing animals.  (This isozyme is heat-labile & can thus be distinguished from the liver isozyme.)
   
   
   
   
    
6. The liver is the main site of cholesterol production. 57% of shunt cases will have low cholesterol.
   
   
   
   
    
7. Ultrasound (you may be able to see the shunting vessel) 
   
        Nuclear medicine
        Transabdominal splenoportography
        Operative mesenteric portography
        Celiac arteriography