Liver Flashcards
What are the functions of the liver?
Metabolism: carbohydrate, lipid, protein, vitamin
Immunologic functions
Detoxification and Excretion: bilirubin, steroids, ammonia, drugs
Digestive: bile acids
What are the 4 anatomic units of the liver?
1) hepatocytes
2) the biliary network
3) the vascular system
4) the Kupffer cells
These are all integrated into a lobule, the functional unit of the liver.
What are the signs of liver disease?
Decreased appetite Lethargy Swollen abdomen (ascites or hepatomegaly) Jaundice Ptyalism Vomiting Neurologic signs (encephalopathy) Weight loss
What are the liver enzyme tests?
Indicators of cell damage: ALT and AST
Indicators of cholestasis/drugs: ALP and GGT
What are liver function tests?
Pseudofunction: Bilirubin (serum and urine) Albumin BUN Cholesterol Glucose
True function:
Ammonia
Bile Acids
What additional tests can you use to assess liver function (besides enzymes and function tests)?
CBC Clotting function tests (PT/PTT) Fecal Abdominocentesis Radiographs Ultrasound Cytology Biopsy
What are the causes of acute hepatitis?
Toxins
Infections
Drugs
Idiopathic
How do you diagnose acute hepatitis?
Increased ALT and AST
ALP much lower than ALT
Bilirubin may be increased
*biopsy is rarely indicated/useful
How do you treat acute hepatitis?
Supportive care- fluids, glucose, nutritional support
Anti-emetics
Antioxidant therapy (N-acetylcysteine, silymarin)
What are causes of chronic hepatitis?
Drug-induced
Copper-associated
Breed related (bedlington terriers, doberman, westie, Dalmatian, labs)
How do you diagnose chronic hepatitis?
BIOPSY
How do you treat chronic hepatitis?
Immunosuppressive therapy
UDCA
Anti-oxidants
Anti-fibrotics
For copper-associated hepatitis:
Dietary copper restirction, chelator therapy, zinc
How can you treat cirrhosis?
Address underlying disease
Anti-fribrotics
Spironolactone +/- lasix
How do you treat hepatic encephalopathy?
Lactulose
Antibiotics
Restricted protein diet
What are the two forms of cholangitis in the cat and what causes each?
Neutrophilic (ascending infection, E.coli)
Lymphocytic (immune-mediated, triaditis)
What do you treat cholangitis in the cat?
General supportive therapy
Depends on biopsy results
Neutrophilic- flluoroquinolone and metronidazole, clavamox
Lymphocytic- prednisolone, ursodeoxycholic acid, chlorambucil
What causes feline hepatic lipidosis?
Rapid weightloss in short time with decreased caloric intake
How do you diagnose feline hepatic lipidosis?
History of anorexia
Fat cat with muscle wasting
Increased ALP with normal GGT
Laparoscopy
Cytology
How do you treat feline hepatic lipidosis?
Treat underlying cause Nutritional support Appetite stimulants (oxazepram, mirtazipine) Anti-emetics (maropitant) Prokinetics (cisapride)
What causes extra-hepatic biliary obstruction in dogs? Cats?
Dogs: pancreatitis, GB mucocele
Cats: neoplasia, liver flukes
How do you treat extra-hepatic biliary obstruction?
If caused by pancreatitis, can be managed medically
For other causes: surgical correction
What are the forms and breed dispositions of portosystemic shunts?
Intrahepatic- large breed dogs (irish wolfhound, old english sheep dogs)
Extrahepatic- cats and small breed dogs (yorkies, min schnauzers, maltese)
What is the clinical presentation for portosystemic shunts?
Young dogs, less active, “don’t do well”
Hepatic encephalopathy signs are common
PU/PD, urate stones, ptyalism, small stature
Cats- small stature, ptyalism, copper irises
How do you diagnose portosystemic shunts?
Lab tests: increase in liver enzymes, decrease in albumin and BUN, urate crystals in urine, microcytic anemia
Lab values may be normal
Ultrasound
CT angiogram
Transplenic scintigraphy
How do you treat portosystemic shunts?
Medical: restricted protein diet, lactulose, +/- neomycin, amoxicillin
Surgical: ligation of shunt (ameroid constrictor, cellophane banding, interventional)
What is the causes hepatic encephalopathy?
Loss of hepatic detoxification function and accumulation of toxic metabolites
What are the clinical signs of hepatic encephalopathy?
Behavior changes Learning difficulties head pressing Blindness Pacing Seizures
How do you diagnose haptic encephalopathy?
Presence of liver dysfunction (bile acids, ammonia)
How do you treat hepatic encephalopathy?
Lactulose
Antibiotics (neomycin, amoxicillin)
Restricted protein diet
How does hepatology in the cat differ from the dog?
You may want to just read the SCAVMA notes (pg 134-135)
Anatomy: cat has a common bile and pancreatic duct that join before entering the duodenal papilla. Some cats may also have a second pancreatic duct. Pancreatitis causes cholestasis much more readily in the cat than in the dog.
Excretion: cats are glucoronyltransferase deficient compared to dog (slower to metabolize some drugs, slower to excrete bilirubin)
Energy requirements: gluconeogenesis pathway in cats never shuts down during fasting as it does in dogs. This predisposes cats to hepatic lipidosis. Cats need arginine, taurine, and glutathione supplementation for proper liver function.
Liver enzymes: AST more difficult to interpret in cat (fasting cat breaks down muscle). Increases in ALP strongly suggest hepatic disease in cats (has a very short half-life).
Bilirubin: Catsdevelop jaundice earlier than dogs (due to decreased glutathione). Renal threshold for bilirubin is nine times higher in cat than dog so bilirubinuria in cat is a reliable sign of hepatic disease
Clotting function: Prolonged PT may be reversed with Vit K in cats
Liver function: Bile acids are very sensitive in cats, hypoalbuminemia is rare in cats with liver diseae
