Liver Pathology

Question 1

general signs of liver disease

Answer 1

1. change in size (inc or dec)
2. change in color/texture/shape
3. enhanced reticular pattern

Question 2

liver cysts

Answer 2

epithelial lined, fluid filled spaces with sporadic distribution

Question 3

multiple biliary cysts

Answer 3

biliary adenocarcinoma; occurs in biliary ducts
- incidental - does not always cause clinical signs
- common in cats

Question 4

acquired cysts

Answer 4

often parasitic; larval stage forms a cyst
- not incidental

Question 5

polycystic disease

Answer 5

cysts replace tissue parenchyma causing a loss of function
- certain breeds predisposed

Question 6

causes of pale liver

Answer 6

1. fibrosis
2. fat
3. inflammation
4. mineral
5. infiltration
6. blood flow
7. necrosis

Question 7

liver fibrosis

Answer 7

deposition of collagen that occurs due to liver damage that leads to scarring
- results in loss of tissue

ex. milk spots in pigs (parasitic cause)

Question 8

liver fat accumulation

Answer 8

causes diffuse pallor
- results in gain of tissue

Question 9

liver inflammation

Answer 9

WBC infiltrates
- results in gain of tissue

ex. infection; causes multifocal pale regions due to hematogenous spread of bacteria

Question 10

liver mineralization

Answer 10

mineral replaces tissue
- results in loss of tissue

Question 11

liver infiltration

Answer 11

ex. tumors
- results in gain of tissue

Question 12

liver decreased blood flow

Answer 12

acute –> pallor
chronic –> fibrosis

infarction is rare in the liver due to dual innervation
- if branches of portal vein become twisted, can cause collapse of portal vein
- leads to blood accumulation behind the torsion –> tissue death

Question 13

liver necrosis

Answer 13

tissue death
- results in loss of tissue

Question 14

normal liver size in small animals

Answer 14

3.5-4% BW

Question 15

normal liver size in large animals

Answer 15

1.5% BW

Question 16

causes of hepatomegaly

Answer 16

1. metabolic abnormalities
2. lack of venous return
3. neoplasia

Question 17

metabolic abnormalities –> hepatomegaly

Answer 17

1. hepatic lipidosis
2. diabetes mellitus
3. hyperadrenocorticism
4. iatrogenic (steroid therapy)

Question 18

hepatic lipidosis

Answer 18

hepatomegaly with diffuse pallor
- negative energy balance causes mobilization of fat stores –> overwhelms with liver –> liver becomes fatty

ex. anorexic fat cat, postparturient cows

Question 19

lack of venous return –> hepatomegaly

Answer 19

1. passive venous congestion
2. primary pulmonary hypertension
3. endocardial fibroelastosis

Question 20

passive venous congestion

Answer 20

right sided heart failure due to thickening in valve causes blockage of blood flow from liver to heart –> blood backs up to the liver –> hepatomegaly due to blood distention –> liver damage

causes hypertension –> ascites

Question 21

common neoplasia in the liver

Answer 21

• hemangiosarcoma
• malignant histocytosis
• lymphoma
• bile duct carcinoma
• hepatic carcinoma

Question 22

causes of microhepatica

Answer 22

1. shunt
2. cirrhosis
3. massive necrosis

Question 23

shunts

Answer 23

congenital or acquired vascular abnormalities that permit blood to bypass the liver and enter systemic circulation directly

Question 24

congenital shunts

Answer 24

single vessel shunts
occurs in young (<1 yr) animals

can be intrahepatic (PDV) or extrahepatic

Question 25

acquired shunts

Answer 25

multiple vessel shunts occurs in older animals cirrhosis/liver disease prevents blood from entering liver --> shunt must form to return blood to heart causes portal hypertension and back flow causes splenic hypertension

Question 26

bloodwork for shunts

Answer 26

increased bile acids and ammonia - bile acids unable to return to liver via enterohepatic circulation - decreased breakdown of ammonia into urea

Question 27

clinical signs for shunts

Answer 27

- neurologic signs (encephalopathy) - microhepatica - ascites - microcytosis

Question 28

cirrhosis

Answer 28

end stage liver disease; liver becomes fibrotic/hard

Question 29

causes of cirrhosis

Answer 29

- chronic toxic exposure - chronic inflammation - biliary obstruction - cardiac cirrhosis etc

Question 30

liver responses to injury

Answer 30

1. nodular regeneration 2. fibrosis 3. biliary hyperplasia

Question 31

outcomes of cirrhosis

Answer 31

- ascites (from portal hypertension and hypoalbuminemia) - acquired intrahepatic shunts

Question 32

massive necrosis

Answer 32

must be necrosis in every lobule of every lobe to cause liver to shrink - ex. hepatotoxic injury

Question 33

hepatotoxic injury

Answer 33

ingestion of substances that are toxic to the liver - causes cell death, lipid accumulation, neoplasia, etc - often causes centrolobular necrosis (site of metabolism)