Changes

Unconjugated bilirubin is sometimes referred to as indirect, in contrast to conjugated which can be referred to as direct bilirubin.

Unconjugated bilirubin is sometimes referred to as indirect, in contrast to conjugated which can be referred to as direct bilirubin.

The conjugated bilirubin is degraded to '''urobilinogen''' by gastro-intestinal bacteria and a small proportion of this product is reabsorbed and excreted in the urine.  The remaining urobilinogen is further degraded to '''stercobilin''', a brown pigment which contributes to the colour of faeces.  Therefore, in animals with complete biliary obstruction, urobilinogen is absent from the urine and the faeces have a white/grey 'alcoholic' colour due to the absence of stercobilin.  The latter alteration in faecal colour also results from steatorrhoea.   

The conjugated bilirubin is degraded to '''urobilinogen''' by gastro-intestinal bacteria and a small proportion of this product is reabsorbed and excreted in the urine.  The remaining urobilinogen is further degraded to '''stercobilin''', a brown pigment which contributes to the colour of faeces.  Therefore, in animals with complete biliary obstruction, urobilinogen is absent from the urine and the faeces have a white/grey 'acholic' colour due to the absence of stercobilin.  The latter alteration in faecal colour also results from steatorrhoea.   

Small quantities of conjugated bilirubin are found in the urine of normal dogs because it has a low renal threshold.

Small quantities of conjugated bilirubin are found in the urine of normal dogs because it has a low renal threshold.