Liver

Question 1

What are the functions of the liver?

Answer 1

Metabolism: carbohydrate, lipid, protein, vitamin

Immunologic functions

Detoxification and Excretion: bilirubin, steroids, ammonia, drugs

Digestive: bile acids

Question 2

What are the 4 anatomic units of the liver?

Answer 2

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.

Question 3

What are the signs of liver disease?

Answer 3

Decreased appetite
Lethargy 
Swollen abdomen (ascites or hepatomegaly) 
Jaundice 
Ptyalism 
Vomiting 
Neurologic signs (encephalopathy) 
Weight loss

Question 4

What are the liver enzyme tests?

Answer 4

Indicators of cell damage: ALT and AST

Indicators of cholestasis/drugs: ALP and GGT

Question 5

What are liver function tests?

Answer 5

Pseudofunction: 
Bilirubin (serum and urine)
Albumin
BUN
Cholesterol
Glucose

True function:
Ammonia
Bile Acids

Question 6

What additional tests can you use to assess liver function (besides enzymes and function tests)?

Answer 6

CBC
Clotting function tests (PT/PTT)
Fecal
Abdominocentesis
Radiographs
Ultrasound
Cytology
Biopsy

Question 7

What are the causes of acute hepatitis?

Answer 7

Toxins
Infections
Drugs
Idiopathic

Question 8

How do you diagnose acute hepatitis?

Answer 8

Increased ALT and AST
ALP much lower than ALT
Bilirubin may be increased

*biopsy is rarely indicated/useful

Question 9

How do you treat acute hepatitis?

Answer 9

Supportive care- fluids, glucose, nutritional support
Anti-emetics
Antioxidant therapy (N-acetylcysteine, silymarin)

Question 10

What are causes of chronic hepatitis?

Answer 10

Drug-induced
Copper-associated
Breed related (bedlington terriers, doberman, westie, Dalmatian, labs)

Question 11

How do you diagnose chronic hepatitis?

Answer 11

BIOPSY

Question 12

How do you treat chronic hepatitis?

Answer 12

Immunosuppressive therapy
UDCA
Anti-oxidants
Anti-fibrotics

For copper-associated hepatitis:
Dietary copper restirction, chelator therapy, zinc

Question 13

How can you treat cirrhosis?

Answer 13

Address underlying disease
Anti-fribrotics
Spironolactone +/- lasix

Question 14

How do you treat hepatic encephalopathy?

Answer 14

Lactulose
Antibiotics
Restricted protein diet

Question 15

What are the two forms of cholangitis in the cat and what causes each?

Answer 15

Neutrophilic (ascending infection, E.coli)

Lymphocytic (immune-mediated, triaditis)

Question 16

What do you treat cholangitis in the cat?

Answer 16

General supportive therapy
Depends on biopsy results

Neutrophilic- flluoroquinolone and metronidazole, clavamox

Lymphocytic- prednisolone, ursodeoxycholic acid, chlorambucil

Question 17

What causes feline hepatic lipidosis?

Answer 17

Rapid weightloss in short time with decreased caloric intake

Question 18

How do you diagnose feline hepatic lipidosis?

Answer 18

History of anorexia
Fat cat with muscle wasting
Increased ALP with normal GGT

Laparoscopy
Cytology

Question 19

How do you treat feline hepatic lipidosis?

Answer 19

Treat underlying cause
Nutritional support
Appetite stimulants (oxazepram, mirtazipine)
Anti-emetics (maropitant)
Prokinetics (cisapride)

Question 20

What causes extra-hepatic biliary obstruction in dogs? Cats?

Answer 20

Dogs: pancreatitis, GB mucocele

Cats: neoplasia, liver flukes

Question 21

How do you treat extra-hepatic biliary obstruction?

Answer 21

If caused by pancreatitis, can be managed medically

For other causes: surgical correction

Question 22

What are the forms and breed dispositions of portosystemic shunts?

Answer 22

Intrahepatic- large breed dogs (irish wolfhound, old english sheep dogs)

Extrahepatic- cats and small breed dogs (yorkies, min schnauzers, maltese)

Question 23

What is the clinical presentation for portosystemic shunts?

Answer 23

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

Question 24

How do you diagnose portosystemic shunts?

Answer 24

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

Question 25

How do you treat portosystemic shunts?

Answer 25

Medical: restricted protein diet, lactulose, +/- neomycin, amoxicillin Surgical: ligation of shunt (ameroid constrictor, cellophane banding, interventional)

Question 26

What is the causes hepatic encephalopathy?

Answer 26

Loss of hepatic detoxification function and accumulation of toxic metabolites

Question 27

What are the clinical signs of hepatic encephalopathy?

Answer 27

``` Behavior changes Learning difficulties head pressing Blindness Pacing Seizures ```

Question 28

How do you diagnose haptic encephalopathy?

Answer 28

Presence of liver dysfunction (bile acids, ammonia)

Question 29

How do you treat hepatic encephalopathy?

Answer 29

Lactulose Antibiotics (neomycin, amoxicillin) Restricted protein diet

Question 30

How does hepatology in the cat differ from the dog?

Answer 30

*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