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1

List the common lab tests enzymes used to test hepatocellular injury and the animals used on and where are they found

ALT - cats and dogs
AST - horses and ruminants
GLDH - horses and ruminants
all found in the cytoplasm and/or mitochondria of hepatocytes

2

List the common lab tests enzymes used to test Cholestasis and the animals used on and where are they found

ALP - cats and dogs
GGT - all major species but more sensitive than ALP in horses and ruminants
membrane bound enzymes to hepatocytes

3

List the 5 liver function tests that can be additionally used on top of the enzymes and what will occur when decrease liver function

1) bilirubin - increase when haemolysis and cholestasis
2) bile acids - normally efficiently recycled - may increase with cholestasis
3) albumin, urea, glucose, cholesterol - all produced by liver may decrease
4) ammonia - normally metabolised into urea see increase
5) coagulation proteins - normally produced by liver so would see decrease

4

examples of things that cause hepatocellular injury, what does the amount of enzyme in serum correspond to

eg hypoxia, trauma, infection, neoplasia, necrosis, toxins, drugs
- serum enzyme activity depends upon the number of hepatocytes injured, severity and duration of injury and enzyme half life - large areas mild may be same as small areas severe

5

ALT what does it stand for, what test, what species, what half-life, what may see in liver failure, where else found in body

Alanine Aminotransferase, hepatocellular injury in dogs and cats, half-life 2-3 days (activity pecks 48hours after injury)
liver failure - may not see increase as most of the functional mass is gone
small amounts found in muscle - increase can be been with severe muscle disease - more in large animals

6

AST what stand for, what testing, what species, what half-life, where else found and what other test then needed and what is the down side

Aspartate Aminotrasnferase (AST), hepatocellular injury, horses and ruminants also for dogs cats but not used
shorter half-life than ALT
also indicator for muscle injury - not as specific as ALT ]
need to interpret alongside creatine kinase (CK) muscle specific enzyme if increase then muscle damage most likely - however only short half-life after 24 hours peak gone so need to also test GLDH

7

GLDH what stand for, what testing, what species, why used

Glutamate dehydrogenas, hepatocellular injury large animals - used as more liver specific than AST but not in dogs and cats because ALT considered superior

8

cholestasis what different to hepatocellular injury in terms of enzyme release, what are the two types and examples of what causes them and if cholestatsis severe what other tests can be used to add evidence

-Increase in circulation takes longer - matter of days rather than hours
- Intrahepatic:
○ constriction of canaliculi
eg lipidosis (diabetes), steroid hepatopathy, neoplasia, fibrosis
- Extrahepatic:
○ intraluminal
eg cholelithiasis, parasites
○ extraluminal
eg neoplasia, inflammation, trauma
severe - hyperbilirubinemia, bilirubinuria, hypercholesterolemia

9

ALP what stand for, what testing, what species, what types

Alkaline Phosphatase, cholestatsis, Dogs and Cats
3 main isotypes (also intestinal, renal and placenta - don't usually contribute)
○ L-ALP: liver (hepatocytes and biliary epithelium)
○ B-ALP: bone (osteoblasts)
○ C-ALP: corticosteroid (hepatocytes) dog specific -

10

What possible causes for an increase in ALP levels

1) cholestasis - increase bile acid increase synthesis of L-ALP
Dog - high sensitivity
Cat - low sensitivity so any increase significant
2) oesteoblast activity B-ALP - bone lesions or bone resorption particularly young and mild increase (less than 4 fold)
3) induction of drugs or hormones -
Corticosteroids - dogs only C-ALP - endogenous or exogenous source
Thyroxine - L-ALP and B-ALP - hyperthyroid cats

11

GGT what stand for, what testing, what animals, where else found, why used and when used

Gamma Glutamyl Transferase, cholestatsis, all but more sensitive ruminants and horses, also found in pancreas, kidney, mammary, epididymis, colostrum (NOT FOALS) - may be indicator of failure of passive transfer
more sensitive than ALP for horses and ruminants
used for pyrrolizidine alkaloid toxicity in cattle (biliary hyperplasia)
and cholelithiasis (stones in the liver), cholangiohepatitis in horses

12

How to calculate fold and how is fold compared

10 times the upper reference interval = 10 fold
•Rule of thumb:
- 2-3 fold increase is considered mildly elevated
- 4-5 moderate
8-10 marked

13

what animal is most predisposed to having anorexia/fasting increase bilirubin in serum (hepatic mechanism)

horses - then cattle then cats but mostly horses

14

Hyperbilirubinaemia testing for liver function species variations in dogs, cats, horses, cattle which useful

dogs - Cholestatic enymes more sensitive than bilirubin
cats - may see before increase in ALP - bilirubinuria always significant
horses - increased bilirubin in health and unconjugated dominants always
cattle - icterus most common due to haemolysis rarely liver disease or cholestasis

15

Delta bilirubin what is it where found in what levels, when increase, half-life, is it excreted in urine

conjugated bilirubin bound to protein, normally very low levels, in cholestasis can increase in serum, long half-life, not excreted in urine

16

3 causes of increase serum bile acids and when never run test for liver function

1) Reduced functional hepatic mass
- impaired extraction of sBA from the portal blood
2) Portosystemic vascular malformations (MVD, PSVA/PSS)
- allows increased proportion of portal blood to bypass the liver (resulting in failed extraction of sBA)
3) Cholestasis - due to regurgitation into circulation - NEVER measure with hyperbilirubinaemia as always elevated in this setting and doesn't tell you information on liver function

17

how to measure bile acid by using a bile acid assays - what species used in, when does it support hepatic insufficiency

Dogs and cats
Two samples - pre and postprandial
○ the preprandial sample (0 hr baseline) requires a 12 hour fast
○ the postprandial sample (2 hr)
- improves sensitivity – challenges the livers capacity for BA extraction
-Give small amount of high lipid content food to challenge the liver and contract the gall bladder
Elevated sBA in absence of cholestasis supports hepatic insufficiency
horse - single sBA sample as no gall bladder

18

ammonia testing what causes high levels, when used, what down side and what other test similar but not on market in australia

1) portosystemic shunt
2) hepatic insufficiency
3) urea toxicosis in ruminants
used when high sBA but no portosystemic shunt evidence in small dogs
downside - unstable ad require special handling to measure
Protein C values - above 70% expected, low values for hepatic insufficiency

19

coagulation protein levels and liver disease why important

may be decreased to an extent to which risk bleeding out so need to ensure if suspect liver damage before take biopsy to test coagulation times

20

List the 4 imaging for the liver

1) radiology
2) ultrasound
3) computed tomography
4) hepatic scintigraphy

21

what is serosal detail in radiology what what can radiology tell us and limitations

the ability to visualise detail within the abdominal caivty depends on intra-abdominal fat
1) liver size and shape
2) radiographic opacity
3) location
limitations
soft/tissue opacity the same so cannot differentiate between gall bladder, biliary tree etc.

22

what is used to detemine size and shape of the liver in radiology what is difficult with cats

gastric axis - imaginary line drawn down gastric fundus and pylorus to asses liver size - normal gastric axis parallel to ribs
caudoventral margin - meant to have sharp point not rounded
lateral projection may have large amount of fat in falciform ligament - just illusion not small liver

23

what occurs when liver too big on radiograph and too small

extends caudally and has a rounded caudo-ventral margin
Gastric axis gets pushed caudo-dorsally
smaller - Gastric axis moved cranially
Apparent decreased distance between the diaphragm and the stomach

24

define the following
anechoic, hyperechoic, hypoechoic, isoechoic

Anechoic
- Region with No Echoes
- Appears black: represents fluid filled structure
Hyperechoic
- Region with High Echo intensity
- Bright: light grey to white
Hypoechoic
- Region with Low Echo Intensity
- Darker grey
Isoechoic
- Equal echogenicity when comparing regions
- Two areas that look the same

25

what cannot be examined in ultrasound, when is ultrasound really useful in conjunction with another structure and what is normal size for biliary tract

hepatic arteries and intrahepatic bile ducts
Ultrasound guided FNA: cytology
- Can guide into mass or nodule within the liver with the use of the ultrasound
FNA - fine needle aspirants
4mm

26

difference between hepatic and portal veins in ultrasound and what can be used to determine flow

portal veins have hyperechoic (bright) walls
colour doppler - more colour more movement within

27

useful structural changes found through ultrasound

- Vascular disease - PSS
- Biliary tract disease
- Choleliths (stones in gall bladder)/ choledocholiths (stones in bile ducts)
- Biliary mucoceles

28

computed tomography what does it do what are the advantages and how used with PSS

X-ray tube that spins around the animal
Takes heaps of images in the transverse plan of the whole body then builds up the body
In the sagittal and dorsal orientations
adv
1) Removes superimposition of adjacent structures
2) Better at differentiating between different soft tissues and between fluid and soft tissues
PSS - add contrast to portal vein within the liver to see where shunt in, how many and whether can do surgery to fix

29

Hepatic Scintigraphy what occurs, what see on screen and why, what application

Radiopharmaceutical as a carrier for a radionuclide
Radionuclide emits gamma rays: detected by a Gamma camera, then creates the image
Black regions indicate increased radiopharmaceutical uptake
Every 4 seconds get another image so the darker the black the more movement of the radiopharmaceutical in that area
when place in colon expect liver to be darker as move through portal vein into the liver then to the heart - PSS get darker heart as bypassing the liver

30

List the 4 important features of pharmacokinetics and define

actions of body on the drug
1) absorption
2) distribution
3) metabolism
4) excretion