Small Ruminant - Liver Dz

Question 1

Gilbert Syndrome is an inherited disorder described in Southdown sheep. Describe the pathophysiology of this syndrome.

Answer 1

Failure of the unconjugated bilirubin to cross the liver cell membrane and be conjugated; most likely caused by a defect in carrier proteins or the conjugating enzyme –> hepatic bilirubin clearance is ~30% of normal.

Question 2

What clinical signs and laboratory test abnormalities are seen in sheep with Gilbert Syndrome?

Answer 2

• Elevated conjugated and unconjugated bilirubin concentrations in serum.
• +/- icterus.
• BSP is not excreted into the bile.
• Liver histo normal other than pigment in the hepatocytes.

Question 3

Dubin-Johnson Syndrome is an inherited disorder described in Corriedale sheep. Describe the pathophysiology of this syndrome.

Answer 3

Failure of conjugated bilirubin to enter the bile canaliculi.
There may be an impairment in excretion of other organic anions as well.

Question 4

What clinical signs and laboratory test abnormalities are seen in sheep with Dubin-Johnson Syndrome?

Answer 4

• Elevated conjugated and unconjugated bilirubin concentrations in serum.
• +/- icterus.
• BSP clearance is delayed.
• Liver histo: hepatocytes contain black, melanin-like pigment.

Question 5

Sheep and goats are more susceptible than cattle to development of disease following infection by liver flukes as they do not mount the same immune response. Describe the acute and chronic forms of fluke infection in sheep.

Answer 5

• Acute: fatal disease, ascites, abdominal haemorrhage, pallor and icterus associated with migration of 5-6000 immature flukes from liver parenchyma to bile ducts 6-10 weeks post-infection.
• Chronic: burdens of >200 flukes; submandibular oedema, ascites, emaciation.

Question 6

What differences are seen on histology of the liver in cattle and sheep following liver fluke infection?

Answer 6

Both have proliferative cholangiohepatitis. The bile duct wall becomes calcified in cattle ~20wk PI, but does not calcify in sheep.

Question 7

Describe the difference in response to infection with Fascioloides magna (the large American liver fluke) in cattle and small ruminants.

Answer 7

• Cattle: encapsulation –> closed cyst in liver.

- Sheep and goats: does not encyst -> migrates un-interrupted –> 1-2 flukes are enough to kill.

Question 8

Is cholelithiasis a clinical disorder of sheep?

Answer 8

No.