Exam 3 - Canine Liver Disease Flashcards
what is the first question you should ask yourself if your patient is showing clinical signs commonly seen in hepatic disease?
is the liver actually diseased
what if your patient has non-specific signs that may or may not reflect hepatic disease? how will you differentiate hepatopathy with vague signs from non-hepatic disease with vague signs?
CLIN PATH!!!!!!!!!!
why can you not expect to see abnormalities in all the panel tests in a patient with significant hepatic disease?
disruption of one hepatic function doesn’t necessitate the disruption of another
T/F: sometimes there are no laboratory changes seen despite major hepatic disease
true
T/F: cholestasis indicates that there is a blocked bile duct when ALP is elevated on the chemistry panel
false - it can be caused by bile duct obstruction from intra-hepatic & extra-hepatic obstruction, but ALP can also be elevated due to drugs (corticosteroids, phenobarbital, primidone)
what are some reasons for ALP to be elevated in a dog?
canine ALP can be elevated due to hepatic disease, extrahepatic biliary obstruction, & endogenous/exogenous steroids
T/F: any increase in ALP in a cat indicates significant disease
true
why may ALP be elevated in a cat?
significant hepatic disease, diabetes mellitus, & hyperthyroidism
what is probably the most common sign seen in animals with hepatic disease?
anorexia
what lab abnormality can sometimes be responsible for CNS signs & mimic encephalopathy?
hypoglycemia
T/F: PU/PD is relatively common in severe hepatic insufficiency, such as animals with portosystemic shunts
true
ascites may be due to ________ or _________ or both
hypoalbuminemia
portal hypertension
what is the classic presentation of an animal with encephalopathy?
animal eats something & starts acting weird 1-3 hours later (CNS signs)
why may we see coagulopathy in animals with hepatic disease?
the liver is where coagulation factors are produced - also easy to cause DIC in organs with slow sinusoidal blood flow
ALT is a very sensitive test of what?
hepatocellular membrane integrity
T/F: normal ALT/ALP eliminates the possibility of hepatic disease
false
T/F: ALT & ALP activities are specific for certain hepatic disorders & you can tell what hepatic disease is occurring based on these values
FALSE - not specific!!!!!!
if you are convinced that there is hepatobiliary disease in your patient, what would be a good way to differentiate between hepatocellular icterus from extrahepatic biliary tract obstruction?
do an abdominal ultrasound looking for evidence of obstruction
T/F: when trying to answer the first question on whether your patient’s liver is diseased, at least one of the diagnostic tests run (chemistry/radiographs/ultrasound/liver function tests) will almost always be abnormal
true
what is the second question you should ask after deciding if the patient’s liver is diseased?
is the hepatic disease clinically important - need to see if the hepatic disease is the CAUSE of the animal’s illness (primary hepatic disease) or if it is the result of the animal’s illness (hepatic disease secondary to other problems)
what is the most common radiographic pattern seen in dogs & cats with hepatic disease? is it helpful?
symmetric hepatomegaly - doesn’t help when trying to determine if the liver disease is important because both primary & clinically insignificant secondary disease may have it
what are some clinical signs associated with liver disease?
anorexia, weight loss, vomiting, PU/PD, ascites, icterus, encephalopathy, & coagulopathy
what are your liver enzyme markers for hepatocellular damage? what are your enzyme markers of cholestasis?
hepatocellular damage - ALT & AST
cholestasis - ALP & GGT
T/F: severe increases in ALT indicates there is irreversible liver damage
false
where is ALT found in the body?
primarily found in the cytosol of hepatocytes making it virtually liver specific
when is ALT released by the liver? can drugs affect this enzyme level?
with increased membrane permeability or hepatocellular necrosis
yes - corticosteroids & phenobarbital can cause mild increases
what are 2 examples of ALT elevations that indicate the need for further investigation?
severely or persistently elevated!!!
single value is >3x the upper limit of normal
value is 2x greater than the upper limit of the reference interval for 4 weeks
T/F: ALT can be increased due to both primary or secondary liver injury
true
what are examples of drugs that can cause elevation of ALT in dogs?
corticosteroids & phenobarbital
what are some examples of primary hepatopathies causing increased ALT?
inflammatory, neoplasia, infectious, trauma, hyperplastic nodules, & vascular issue
what are some examples of secondary hepatopathies causing increased ALT?
endocrine problem, inflammatory disease, hypoxia, & metabolic issue
why is AST less liver specific than ALT as a marker of hepatocellular damage?
it is found in the cytosol & mitochondria of hepatocytes (I think muscle cells too) - can be increased with myopathies!!!
T/F: increases in AST parallel those of ALT which explains why corticosteroids & phenobarbital can cause mild increases in both
true
what are the 2 main isoforms of the non-specific ALP gene?
liver & bone!!!!
what is the intestinal ALP gene that is clinically important to consider in dogs?
glucocorticoid induced isoform of ALP
where is ALP found in the body?
it is bound to the membranes of the hepatocytes that form the bile canaliculi & sinusoids
what is ALP a sensitive marker for? is it liver specific?
cholestasis - both intrahepatic & extrahepatic disease
not liver specific
T/F: increases in serum ALP may not be clinically significant in dogs
true
what are some examples of why the bone isoform of ALP may cause increased serum levels?
growth, osteolytic disease, hyperparathyroidism, & idiopathic
what are some examples of why the steroid isoform of ALP may cause increased serum levels?
iatrogenic
hyperadrenocorticism
what are some examples of why the liver isoform of ALP may cause increased serum levels?
hepatic parenchymal disease - nodular hyperplasia, vacuolar hepatopathy, toxicity, chronic hepatitis, & neoplasia
biliary tract disease
extra-hepatic disease
increases in GGT parallel increases in what other enzyme?
ALP
what is GGT a sensitive marker of?
cholestasis
what induces GGT release?
corticosteroids
where is GGT found in the body?
bound to the membrane of the hepatocytes that form the bile canaliculi & bile ducts
also produced by extra-hepatic tissues
after answering whether the liver is diseased, what 2 questions should you consider next?
- is the liver disease clinically important?
- are there any obvious extra-hepatic causes?
what clinical pathology findings may indicate liver dysfunction on a chemistry panel?
decreases in - albumin, cholesterol, glucose, & BUN
increases in - bilirubin
T/F: dogs with severe hepatic disease can have normal liver function tests
true
what tests can you use to evaluate liver function?
preprandial & postprandial serum bile acids
serum ammonia
what are abdominal rads useful for when working up liver disease?
assessing hepatic size
looking for masses
looking for extra-hepatic disease
what is an abdominal ultrasound useful for when working up liver disease?
evaluating the hepatic parenchyma & biliary tract
looking for extra-hepatic disease
T/F: dogs with liver disease can have normal ultrasound evaluations
true
what is the final question you should consider when approaching a liver disease case?
should you biopsy the liver
what does hepatic cytology not allow you to do?
can’t assess hepatocellular architecture
T/F: some liver diseases can be diagnosed based off of a liver FNA/cytology
true