Equine Liver

Question 1

What is jaundice?

Answer 1

Retention of bilirubin

Unconjugated form is more prominent in horses

Question 2

What disease can mask jaundice and why?

Answer 2

Sepsis, as the mm are deep red/blue

Question 3

Give some clinical signs of liver disease

Answer 3

Jaundice
Weight loss
Depression/CNS signs
Photosensitisation (accumulation of phylloerythrin from chlorophyl)
Haemorrhage 
Colic
Oedema (due to hypoalbuminaemia, rare)
Diarrhoea
Dyspnoea (usually Ragwort; laryngeal paralysis)
Anorexia/inappetence

Question 4

How would you diagnose liver disease?

Answer 4

Liver enzymes
Serum bilirubin
Liver function tests (bile acids)
Blood ammonia (hyperammonaemia)

Question 5

Give the functions of the liver

Answer 5

Digestive and secretory (bile salts)
Metabolic (CHO, protein, fat metabolism)
Detoxification/excretory 
Synthetic (clotting factors, proteins)
Storage (vitamins, minerals)

Question 6

Elevated GGT would indicate disease where?

Answer 6

Mainly biliary tract

Also specific to liver and pancreas

Question 7

Elevated AST indicates what?

Answer 7

Hepatocellular damage

Question 8

Elevated SDH indicates what?

Answer 8

Hepatocellular damage

Question 9

What is the best test for liver function?

Answer 9

Bile acids
Continuous production so no need to fast
Correlated with severity

Question 10

High blood ammonia levels may then cause what?

Answer 10

Encephalopathy (decline in brain function)

Question 11

Which clotting factor has the shortest half life so is the first to have a prolonged PT (prothrombin time) when testing liver function?

Answer 11

VII

Question 12

Give some risks of performing a liver biopsy

Answer 12

Haemorrhage (don't do if clinical coagulopathy)
Inappropriate sample eg focal lesions
Negative culture
Infections
Pneumothorax (rare)

Question 13

Give some advantages of performing a liver biopsy

Answer 13

Biopsy score is the best indicator of prognosis in liver disease
(>6= poor prognosis)

Question 14

Give some clinical signs of ragwort poisoning

Answer 14

Frequently only see signs of liver failure just prior to death
Early clinical signs are hard to difficult to detect and non-specific:
weight loss, behavioural change, anorexia
Other signs: inspiratory dyspnoea (laryngeal paralysis), severe CNS signs (hepatic encephalopathy), colic (gastric impaction), photosensitisation, haemorrhages, icterus

Question 15

How do you diagnose ragwort poisoning?

Answer 15

History
Clinical presentation
Clinical pathology (GGT best enzyme to screen)
US (small liver may be difficult to find)
Biopsy (may not always see megalocytosis)

Question 16

How do you treat ragwort poisoning?

Answer 16

Probably shouldn’t treat if bile acids >50 umol/L (>20=poor prognosis)
Can try supportive therapy (fluids, electrolytes, glucose)
Reduce hepatic encephalopathy (moderate to low protein diet, high branched chain amino acids -BCAAs, neomycin or metronidazole)

Question 17

What causes cholangiohepatitis and cholelithiasis?

Answer 17

Ascending bile duct infection form GIT

Gram-negatives deconjugate bilirubin -> precipitates out and causes choleliths

Question 18

Give the clinical signs of cholangiohepatitis and cholelithiasis

Answer 18

Fever, jaundice, colic
Marked increase in liver enzymes esp GGT
Biopsy may yield a positive culture (neutrophilic inflammation)

Question 19

How would you treat cholangiohepatitis and cholelithiasis?

Answer 19

Long-term antibiotic therapy

Question 20

What is chronic active hepatitis?

Answer 20

Any progressive inflammatory hepatitis

Biopsy may indicate immune-mediated (plasmocytic-lymphocytic)

Question 21

How should you treat chronic active hepatitis?

Answer 21

Corticosteroids or other immunosuppressive medications eg azathioprine

Question 22

Give the clinical signs of acute hepatitis

Answer 22

Severe CNS signs, jaundice, discoloured urine

Question 23

Give some risk factors for hyperlipaemia

Answer 23

Breed
Obesity
Females
Age vs insulin sensitivity (older)
Underlying disease
Transport, stress, lactation
Starvation

Question 24

Describe the pathogenesis of hyperlipaemia

Answer 24

Breakdown of stored fat (hormone-sensitive lipase) -> fatty acids to liver -> energy
Liver has poor ketogenic capability -> energy production is overwhelmed -> trigylcerides accumulate in liver and in plasma -> hyperlipaemia -> liver failure -> death
Ideally want to promote re-uptake in periphery by LPL (lipoprotein lipase) but LPL can’t keep up with HSL and liver

Question 25

Give some presenting signs of hyperlipaemia

Answer 25

Non-specific: anorexia, weakness, lethargy, progress to more severe CNS and other signs
Signs may be due to hyperlipaemia, underlying disease, or secondary liver disease
Be aware of at risk animals eg colic surgery

Question 26

How do you diagnose hyperlipaemia?

Answer 26

Cloudy serum
-Triglycerides >5 mmol/L = hyperlipaemia
-Triglycerides <5 (but over 1.5) = hyperlipidaemia
Presence of liver disease, azotaemia (inhibits LPL-lipprotein lipase)

Question 27

How do you treat hyperlipaemia?

Answer 27

Treat underlying disease and parasites
Positive energy balance
Correct dehydration, electrolyte imbalance, acidosis
Other symptomatic therapy
Normalisation of lipid metabolism
-Insulin therapy? Risk of laminitis. Don’t give unless you have to.

Question 28

What is the prognosis like for hyperlipaemia?

Answer 28

Guarded to poor
Worse if female, other organ involvement, poor initial response, failure to eat
Get horse out of the box

Question 29

Give 2 causes of jaundice

Answer 29

Anorexia (causes hyperbilirubinaemia)

Haemolysis

Question 29

How do you distinguish between the liver and spleen on ultrasound?

Answer 29

Spleen is more hyperechoic (brighter/more white) than liver

Question 30

What should you do before taking a liver biopsy?

Answer 30

Check clotting profile