Hyperbilirubinemia in sick cattle.

Hyperbilirubinemia was present in 387 out of 1279 sick cattle admitted to the clinic of the Ontario Veterinary College. One hundred and ninety five of these had a total serum bilirubin of 17 mumol/L or greater. Clinical records, laboratory data and when available, pathology reports from these 195 animals were examined in an attempt to explain the reason for the high bilirubin levels. The hyperbilirubinemia in 187 of these was mainly due to an increase in unconjugated bilirubin. Jaundice, liver disease or anemia was not a feature and alkaline phosphatase was not elevated. The 195 animals with hyperbilirubinemia suffered from a variety of diseases that seemingly were unrelated to the increased bilirubin. The most frequently described signs were anorexia and rumen stasis. Liver disease was diagnosed in eight animals and in these clinical jaundice, and increased conjugated bilirubin and alkaline phosphatase was a feature. It was concluded that hyperbilirubinemia occurred in many diseases of cattle and in most instances was related to a failure of the liver to remove unconjugated bilirubin from the serum rather than to a failure of the liver to excrete conjugated bilirubin.