Liver

Question 1

hepatic acinus

Answer 1

functional unit of the liver

extends from the hepatic triad to the central vein

Question 2

central vein

Answer 2

vein located in the center of each liver lobule that receives nutrient rich blood after it passes through the sinusoids and carries it to the hepatic vein

Question 3

sinusoids

Answer 3

fenestrated sinuses between each hepatocyte that allows for exchange of nutrients and absorption and secretion of products

hepatocytes detoxify blood as it passes through the sinusoids

Question 4

portal triad

Answer 4

portal vein + hepatic artery + bile duct

Question 5

portal vein

Answer 5

provides 80% of the blood and 50% of oxygen to the liver

Question 6

hepatic artery

Answer 6

provides 20% of blood supply and 50% of oxygen to the liver

Question 7

bile duct

Answer 7

collects bile from the bile canaliculi as it’s produced by hepatocytes

Question 8

zone 1

Answer 8

periportal (closest to hepatic triad)

receives the most oxygen + nutrient rich blood

Question 9

zone 3

Answer 9

centrilobular (closest to the central vein)

receives the least oxygen + nutrients

site of CYP450 metabolism
most susceptible to hypoxic injury

Question 10

what are the clinical signs of liver disease

Answer 10

1. subclinical
2. non-specific - anorexia, weight loss, vomiting, weakness, lethargy
3. specific - icterus, ascites, PU/PD, neuro signs, pigmenturia, fever, melena, acholic feces

Question 11

what are the 5 liver function parameters

Answer 11

• albumin
• BUN
• cholesterol
• glucose
• bilirubin

Question 12

what are two highly specific liver tests

Answer 12

• bile acids
• blood ammonia

Question 13

bile acids test

Answer 13

detects liver dysfunction even if albumin, BUN, cholesterol, glucose, and bilirubin are normal

ELEVATED with portosystemic shunts or hepatobiliary disease

sample 1: fasted
sample 2: 2 hours post meal

Question 14

when should a bile acids test NOT be used

Answer 14

hyperbilirubinemia

redundant, BA will be high (exception: prehepatic hyperbilirubinemia - bile acids will be normal)

Question 15

blood ammonia

Answer 15

ELEVATED with portosystemic shunts

1 fasted sample

better in dogs than cats

Question 16

liver enzymes

Answer 16

evaluates the degree of liver damage/leakage and cholestasis NOT function

ALT
AST
ALP
GGT

Question 17

ALT (alanine aminotransferase)

Answer 17

hepatocellular leakage

located in cytosol - increases with minimal damage

liver ONLY
if >2x upper limit –> ALWAYS significant

Question 18

AST (aspartate aminotransferase)

Answer 18

hepatocellular leakage

located in mitochondria - increases with severe damage

liver & skeletal muscle
- always evaluate alongside CK

Question 19

ALP (alkaline phosphatase)

Answer 19

cholestatic enzyme
- indicates impaired bile flow

liver, bone, corticosteroid
- corticosteroid ONLY in dogs

comes from hepatocytes near bile canaliculi

Question 20

GGT (gamma glutamyl transferase)

Answer 20

cholestatic enzyme
- indicates impaired bile flow

liver only

comes from hepatocytes near the bile duct

Question 21

hepatocellular hepatopathies

Answer 21

elevated ALT, AST

Question 22

cholestatic hepatopathies

Answer 22

elevated ALP, GGT

Question 23

mixed hepatopathies

Answer 23

elevated ALT (+/- AST), ALP, GGT

Question 24

what liver parameters are always relevant in cats

Answer 24

bilirubinuria
elevated ALP (no corticosteroid induced)

Question 25

why does triaditis only occur in cats

Answer 25

common bile duct + pancreatic duct converges prior to entering the duodenum

Question 26

primary vs secondary hepatopathies

Answer 26

primary - liver disease causing a hepatopathy secondary - reactive hepatopathies

Question 27

what is the most common cause of reactive hepatopathy

Answer 27

GI disease others: dental disease, diabetes, hypoxemia, hyperlipidemia, hyperthyroidism, pancreatitis, R-CHF

Question 28

non-specific reactive hepatitis

Answer 28

commonly occurs with GI diisease due to liver receiving splanchnic blood flow (from abdominal viscera) containing inflammatory cytokines, GI endotoxins, etc leading to hepatic inflammation WITHOUT hepatocyte death

Question 29

what are the common feline hepatic diseases

Answer 29

1. hepatic lipidosis 2. cholangitis 3. neoplasia 4. reactive hepatopathy 5. vascular, toxic, FIP

Question 30

how should caloric requirements be calculated for refeeding a hepatic lipidosis cat

Answer 30

resting energy requirements (RER) tube feed in increments of 20% RER daily (day 1 = 20% RER, day 2 = 40% RER, etc)

Question 31

resting energy requirement equation

Answer 31

linear: RER = (BW x 30) + 70 - only in patients >2kg and <40kg log: RER = 70 x BW^0.75

Question 32

what are the three forms of feline cholangitis

Answer 32

1. neutrophilic (most common) 2. lymphocytic 3. liver flukes

Question 33

can you differentiate between neutrophilic and lymphocytic cholangitis on imaging or labwork

Answer 33

no - requires histopathology

Question 34

what are the common canine hepatic diseases

Answer 34

1. reactive hepatopathy 2. immune mediated chronic hepatitis 3. copper associated chronic hepatitis 4. portosystemic shunts & portal venous hypoplasia (PVH) 5. hepatic neoplasia 6. superficial necrolytic dermatitis

Question 35

hepatic encephalopathy

Answer 35

accumulation of ammonia due to decreased liver function liver unable to convert ammonia into urea for excretion --> excess ammonia causes damage to astrocytes

Question 36

treatment of hepatic encephalopathy

Answer 36

1. antibiotics (amoxicillin) - goal is to decrease urease producing bactera 2. lactulose - changes colon pH to acidify NH3 to NH4, provides alternate nutrient source for urease producing bacteria, and causes osmotic diuresis by pulling water into colon and promoting rapid passage through colon 3. restrict dietary protein - decreases ammonia production

Question 37

what is ursodeoxycholic acid

Answer 37

ursodiol increases bile flow (choleretic) anti-inflammatory, immunomodulatory, and antifibrotic

Question 38

what is denamarin

Answer 38

SAMe + silybin antioxidants - protects from oxidative damage

Question 39

how to biopsy a liver if suspected chronic hepatitis

Answer 39

1. rule out lymphoma via FNA 2. perform coagulation panel 3. obtain 5+ liver biopsies from 2+ liver lobes (3 for histo, 1 for culture, 1 for copper quantification)

Question 40

what is chronic hepatitis

Answer 40

non-specific inflammation of the liver due to an underlying etiology - immune mediated - copper accumulation - infectious - drug induced (tetracyclines, phenobarbital)

Question 41

what histopathologic features are seen with immune mediated chronic hepatitis

Answer 41

normal chronic hepatitis features plus: - interface hepatitis - hepatocyte death at limiting plate

Question 42

interface hepatitis

Answer 42

inflammation extending past the limiting plate into the parenchyma limiting plate: separates the triad from the hepatic parenchyma

Question 43

what histopathologic features are seen with copper associated chronic hepatitis

Answer 43

normal chronic hepatitis features plus: - rhodanine staining of copper accumulations in centrilobular regions (accumulates in zone 3 but progresses periportal) - pigment granulomas - NO interface hepatitis

Question 44

pigment granulomas

Answer 44

aggregates of macrophages with copper granules

Question 45

congenital portosystemic shunts

Answer 45

SINGLE shunts intra or extrahepatic small breeds: single extrahepatic large breeds: single intrahepatic

Question 46

acquired portosystemic shunts

Answer 46

MULTIPLE shunts intra or extrahepatic