Problem base approach to jaundice (icterus)

Question 1

Jaundice

Answer 1

Yellow discoloration of body tissues caused by ↑ levels of BR
Mostly seen on sclera, mm, non-pigmented skin

Question 2

How is BR formed?

Answer 2

Breakdown of Hb from aged RBCs reticuloendothelial system
Small amounts from myoglobin, heme-containing liver enzymes

Question 3

System/ location

Answer 3

Hemopoietic (RBCs) v hepatobiliary (liver/ biliary)
OR
Prehepatic (RBC breakdown) v hepatic (physically affecting the liver) v posthepatic
AND
Sepsis/ severe inflammation (uncommon)

Question 4

Defining the system

Answer 4

Differentiating between hematopoietic (pre-hepatic) jaundice from hepatobiliary jaundice

Question 5

How do you differentiate between hematopoietic (pre-hepatic) jaundice from hepatobiliary jaundice?

Answer 5

Animals with red cell hemolysis severe enough to result in jaundice will always have significant regenerative anemia

Question 6

Microangeiopathic causes of hemolytic anemia

Answer 6

Splenic torsion, hemangiosarcoma, caval syndrome
Hypophosphatemia in diabetes mellitus

Question 7

Other causes of hemolytic anemia

Answer 7

Congenital: pyruvate kinase deficiency and phosphofructokinase deficiency
Drugs/ toxin: Heinz bodies from garlic, onion, zinc

Question 8

Most common causes of hepatic jaundice in dogs

Answer 8

Chronic inflammatory hepatitis*
Neoplasia (lymphoma)
Toxic hepatits
Infectious hepatitis (leptospirosis and adenovirus)

Question 9

Most common causes of hepatic icterus in cats

Answer 9

Cholangiohepatitis (acute or chronic neutrophilic and chronic lymphocytic)
FIP
Neoplasia
Hepatic lipidosis (depends on geographic locaiton)

Question 10

Post-hepatic jaundice causes

Answer 10

Toxic/ infectious cholangitis
Pancreatic disease (pancreatitis, abscess, carcinoma)
Biliary lesions (abscess, neoplasm, mucocele, cholelithiasis)
Bile duct rupture
Intestinal pathology causing obstruction of bile flow @ common bile duct

Question 11

What is a non-hepatic cause of jaundice in horses?

Answer 11

Starvation → anorexia is the most common cause of jaundice

Question 12

Non-hepatic causes of jaundice

Answer 12

Fever, starvation, sepsis/ significant inflammation (esp in cats)

Question 13

BR in dogs

Answer 13

Low renal threshold
Renal enzymes produce and conjugate to a limited extent
Mild BR (2+) can be normal

Question 14

BR in cats

Answer 14

Cats have 9x higher threshold so any BRuria is pathological