2. Liver Flashcards
liver test for small animals
not useful in ruminants, horse, pigs due to low activity in liver
ALT (Alanine aminotransferase)
primary liver enzyme used in large animals
AST (aspartate aminotransferase)
SENSITIVE — hepatocellular injury (most spp)
not specific
found in striated muscles & erythrocytes
AST
released by leakage or lysis
cytoplasmic isoforms
only released by cell lysis
mitochondrial isoform
may indicate severe liver injury in dogs & cats
also concurrent hepatic & muscle injury
AST that approaches ALT
Half life of AST in canine
12 hours
Half life of AST in feline
~1.5 hours
Half life of AST in bovine
~2 days
Half life of AST in equine
~2 days
liver-specific in all species, primarily used in LARGE animals in place of ALT
— in cytosol
— low enzyme stability in vitro hampers use
Sorbitol dehydrogenase (SDH)
found in liver & other tissues
NOT specific — hepatocellular injury
little useful information
Lactate dehydrogenase (LDH)
a mitochondrial enzyme, liver specific in all species
not widely used
Glutamate dehydrogenase (GLDH)
physical obstruction of bile flow that occurs intra/extrahepatic
— hepatic lipidosis
— gallstone
cholestasis
enzymes located on the canalicular membrane of hepatocyte and biliary epithelium whose synthesis is induced by cholestasis (and by some drugs)
cholestatic enzymes
special assays exist for isoforms;
however, this is only occasionally useful in determining specific cause of increased SAP
enzyme isoforms
→ makes up most of SAP in healthy adult animals of most species
→ Activity increases with cholestasis and with certain drugs
liver SAP isoform
→ Makes up to 10-30% of total SAP in healthy dogs
→ Increased activity of total SAP within 3-4 days upon exposure to corticosteroids and certain drugs
→ Liver SAP isoenzyme increases first followed by corticosteroid-induced AP isoenzyme in 7 days
only in DOGS
Corticoteroid induced SAP isoform
Makes up a small amount of SAP in
healthy adult animals
→ Total SAP is 2-3X higher in young
growing animals
due to the presence of more bone SAP, esp. in horses
→ Increases with bone pathology (~2-4X)
fracture healing
bone tumors
metabolic bone disease
Bone SAP isoform
important serum SAP of rodents
Intestinal SAP
generally do not appear in serum due to very short half-lives (minutes)
Kidney & Placenta SAP
increased delivery of bilirubin to hepatocytes primarily as a result of hemolytic anemia or less often
secondary to massive internal hemorrhage
(e.g., hemoabdomen)
Prehepatic jaudice
greater than 50% of bile flow is obstructed
- hepatic lipidosis
- feline cholangiohepatitis
Hepatic jaundice
Cause:
- Partial or complete obstruction of bile duct with regurgitation of Bc into circulation and minor reduction in Bu uptake
- Leakage of bile from ruptured gall bladder or bile duct
Examples:
1. gallstones
2. pancreatic abscess/neoplasm regional lymphadenopathy
urine → absence of urobilinogen (in theory)
feces → gray (severe/chronic)
leads to intraheptic disease
Posthepatic jaundice
