Equine Liver Disease

Question 1

What percentage of the functional capacity of the liver must be lost for hepatic function to be impaired?

Answer 1

80%

Question 2

What clinical signs are seen in stage 1 of hepatic encephalopathy in equine patients?

Answer 2

Subtle impairment of intellect

Question 3

What clinical signs are seen in stage 2 of hepatic encephalopathy in equine patients?

Answer 3

Motor function, intellectual ability and consciousness impaired: depression, head pressing, circling, ataxia, aimless walking

Question 4

What clinical signs are seen in stage 3 of hepatic encephalopathy in equine patients?

Answer 4

Aggressive
Periods of stupor
Recumbent
Coma

Question 5

List two aspects of the pathophysiology of equine hepatic encephalopathy.

Answer 5

Accumulation of toxins in the blood
Augmented activity of inhibitory neurotransmitters

Question 6

How would you diagnose equine hepatic encephalopathy?

Answer 6

Prescence of neurologic signs of cerebral dysfunction with physical examination and laboratory findings compatible with liver disease.

Question 7

What is regurgitation icterus?

Answer 7

Impaired excretion of bilirubin into the biliary tract.

Question 8

What is the most consistent clinical sign of equine liver disease?

Answer 8

Weight loss

Question 9

How does liver disease cause photosensitisation in horses?

Answer 9

There is an increase blood concentration of a photodynamic agent - phylloerythrin. UV and phylloerythrin causes free radicals and therefore cell membrane damage and necrosis.

Question 10

What are the fractions that make up the value of total bilirubin?

Answer 10

Conjugated (direct) and unconjugated (indurect)

Question 11

What does an increase of over 25% of conjugated bilirubin mean in relation to equine liver disease?

Answer 11

More specific to hepatic disease

Question 12

What does an increase of over 30% of conjugated bilirubin mean in relation to equine liver disease?

Answer 12

Cholestasis

Question 13

The quantitaion of which substance is an excellent screen of liver failure in horses?

Answer 13

Serum bile acid concentration

Question 14

For how long and what percentage of the liver must have been affected for hypoalbuminaemia to occur?

Answer 14

> 80% of the liver affacted
3 weeks

Question 15

List three liver specific and non-inducible liver enzymes that are specific for hepatocellular disease in horses.

Answer 15

SDH, ARG and GLDH

Question 16

List four liver enzumes which are also found in other tissues and are inducible in horses

Answer 16

AST, ALP, LDH, ALT

Question 17

What is the most specific enzymes for hepatic disease in horses?

Answer 17

GGT

Question 18

What are the two first line lab tests for evalation of liver damage and function?

Answer 18

Damage -GGT
Function - Bile acids

Question 19

How should you diagnose liver disease in horses?

Answer 19

Biopsy (ultrasound guided)

Question 20

What is the best method to manage diest insufficiency in horses?

Answer 20

Diet

Question 21

List three methods of reducing absorption of toxic metabolites by enteric bacteria.

Answer 21

Paraffin/magnesium sulphate by nasogastric tube
Neomycin, metronidazole.
Lactulose

Question 22

List three causes of acute heptic insufficiency in horses

Answer 22

Theiler’s disease
Bacterial Hepatitis
Hepatic lipidosis

Question 23

What usually causes Theiler’s disease?

Answer 23

Horses will usually have recieved an equine origin antiserum 4-10 weeks before.

Question 24

What is the most common cause of chronic cause of chronic liver failure in horses?

Answer 24

Megalocytic hepatopathy (ingestion of pyrrolizidine alkaloid containing plants)

Question 25

How does megalocytic hepatopathy work in the liver?

Answer 25

Cumulative toxicity
Toxin stops cell division so hepatocytes enlarge (megalocytes)
When megalocytes die there is fibrosis
Extensive fibrosis results in the liver shrinking, leading to failure.