Jaundice (Icterus)
- this is a staining of the tissues with bilirubin or bilirubin complexes
- bile pigments have a strong affinity for elastic tissue and thus the yellowish colour can be easily seen in the sclera and mucous membranes in life and in the aorta at necropsy
- the serum bilirubion level gives an indication of the degree of icterus
- dog's normal range is usually below 0.5mg/100ml
- level is at least 2mg/100ml when jaundice is clinically evident
Causes
- overproduction of bilirubin
- eg haemolytic crises
- diffuse liver disease
- where there is a decreased uptake, conjugation, and secretion of bilirubin
- reduced outflow of bile into the gut
- intrahepatic biliary obstruction eg foreign bodies, tumours, or fibrosis
Classification types
Haemolytic jaundice
- due to increased red cell destruction
- results in increased amounts of bilirubin in the reticuloendothelial system
- the production may be at a rate which exceeds the capacity of the liver to conjugate and eliminate it
- most of bilirubin is unconjugated
- bile pigment is not excreted in the urine
- since the kidney can excrete only the water soluble conjugate
- diseases
- Babesiosis
- isoimmune reactions eg newborn foal whose dam has elaborated specific antibody against its red cells
Obstructive jaundice
- due to bile duct obstruction
- accumulation of conjugated bilirubin
- bile pigment is excreted in the urine
- bile pigment will be diminished in the faeces
- diseases
- carcinoma involving the head of the pancreas
Hepatocellular jaundice
two factors are concerned in the production of jaundice following liver cell damage