Icterus

Question 1

Define Icterus

Answer 1

Hyperbilirubinaemia - excess bilirubin in the blood

Question 2

Newly formed _______ bilirubin is ______ and binds to _____

Answer 2

unconjugated - insoluble - albumin

Question 3

What do hepatocytes conjugate bilirubin with to make it water soluble?

Answer 3

Glucuronic acid

Question 4

What is the main cause of pre-hepatic icterus?

Answer 4

Haemolysis - conjugation and uptake of bilirubin into liver overwhelmed

Question 5

What is the main cause of hepatic icterus?

Answer 5

Poor uptake - conjugation and excretion of bilirubin in hepatocytes overwhelmed

Question 6

What is the main cause of post-hepatic icterus?

Answer 6

Cholestasis

Question 7

What GIT signs give you a clue towards icterus?

Answer 7

Vomiting, diarrhoea, acholic (white) faeces, melaena (dark sticky faeces), ascites (abdominal effusion)

Question 8

What Neurological signs give you a clue towards icterus?

Answer 8

Personality change, head pressing, ptyalism (excessive saliva), head pressing, disorientation, seizures, stupor

Question 9

What Renal and Urinary changes give you a clue towards icterus?

Answer 9

PU/PD, stranguria (difficulty urinating), bilirubinuria

Question 10

Give an example of differential diagnosis for pre-hepatic icterus in small animals

Answer 10

Immune Haemolytic Anaemia - Babesia infection - Toxins

Question 11

Give an example of differential diagnosis for hepatic icterus in cats

Answer 11

Suppurative cholangiohepatitis - Lymphocytic plasmacytic hepatitis - Hepatic lipidosis - Feline infectious peritonitis - Toxins - Neoplasia

Question 12

Give an example of differential diagnosis for hepatic icterus in dogs

Answer 12

Acute liver disease - Leptospirosis - Chronic hepatitis - Neoplasia

Question 13

Give an example of differential diagnosis for post-hepatic icterus in small animals

Answer 13

Pancreatitis - Neoplasia - Cholelithiasis (stones in bile duct)

Question 14

How would you differentiate between pre-heptic and hepatic icterus?

Answer 14

Packed Cell Volume (PCV) test and Total Solids (TS)
Pre = low PCV, normal TS
Hepatic = normal PCV, low TS (IF albumin production affected)

Question 15

How would you differentiate between hepatic and post-hepatic icterus?

Answer 15

Imaging - X-rays, radiographs, ultrasound

Question 16

Liver _____ elevations are common in small animals, mostly _____ ______ to hepatocytes

Answer 16

Enzyme - reversible damage

Question 17

Name the significant liver enzymes

Answer 17

ALT (specifically liver) - AST (present in muscle and intestines) - AP (biliary duct cells)

Question 18

What would idicate liver failure on a chemistry profile?

Answer 18

Low albumin - low cholesterol - low glucose - low BUN (blood urea nitrogen)

Question 19

What is usually elevated in liver failure or portosystemic shunts?

Answer 19

Bile acid levels

Question 20

What is hepatic encephalopathy? Give a clinical sign of it

Answer 20

NH3 and aromatic AA go directly into blood and exposed to the CNS - neurological problems or urate stone formation

Question 21

What is the pathogenesis of hepatic encephalopathy?

Answer 21

Increased ammonium in blood - decreased ability to convert uric acid to allantoin in liver so more urate excreted in urine

Question 22

In horses, what protein is responsible for unconjugated bilirubin uptake?

Answer 22

Ligandin

Question 23

How come sometimes animals with liver failure don’t show any obvious clinical signs?

Answer 23

Liver has a large capacity for regeneration

Question 24

In horse photosensitization, _______ (photodynamic agent) is formed by gut bacteria, absorbed and conjugated by the _____

Answer 24

Phylloerythrin - Liver

Question 25

How can liver dysfunction cause photosensitization?

Answer 25

Increased levels of phylloerythrin cause UV light to be absorbed more efficiently causing damage and necrosis to non-pigmented areas

Question 26

Give an example of three substances that will go up in a horses bloodwork when they have liver disease

Answer 26

Bile acids - SDH - GGT

Question 27

When would bile acids increase in the blood of a horse?

Answer 27

Anorexia and obstructive disease

Question 28

When does SDH increase in a horses bloodwork?

Answer 28

Acute liver disease

Question 29

When does GGT increase in a horses bloodwork?

Answer 29

During Cholestasis

Question 30

How can the diet of a hepatic encephalopathy horse be altered for treatment?

Answer 30

High carbohydrate and limited protein - enough to maintain so as not to cause malnutrition

Question 31

How does ragwort cause hepatic disease in horses?

Answer 31

Pyrrolizidine alkaloids metabolised by liver to toxic pyrrole - these are antimitotic causing megalocyte production and fibrosis in hepatocytes

Question 32

Give 5 examples of acute hepatitis in horses

Answer 32

Theiller’s disease - Tyzzer’s disease (bacterial) - Toxins - Viral (equine herpesvirus) - Parasitic (migration)

Question 33

What is Tyzzer’s disease caused by? What does it do to the liver?

Answer 33

Clostridium piliformis - multifocal hepatitis and enteritis

Question 34

How can you diagnose choleithiasis in horses?

Answer 34

Liver enzyme activity (increased GGT, SDH, AST) - Ultrasound - Biopsy

Question 35

What is hyperlipaemia commonly caused by?

Answer 35

Negative energy balance - stress, disease, pregnancy, lactation

Question 36

What is the pathogenesis of hyperlipaemia in horses?

Answer 36

Increased fatty acid production because of negative energy balance = greater Triglyceride production in liver