Clinical implications of feline bilirubinuria

In a retrospective survey of 227 urinalyses obtained from 82 normal adult male cats, bilirubinuria was not observed. Bilirubinuria was detected in 38 (3.6%) of 1054 samples obtained from client-owned cats. Only 32 (4.0%) of 808 client-owned cats that had urinalyses performed during the study exhibited bilirubinuria. Review of medical records revealed that all 32 bilirubinuric cats were ill when urine samples were analyzed. Twenty-three of the 32 cats had liver diseases that were categorized as primary or secondary to diabetes mellitus, feline infectious peritonitis, neoplasia, or feline leukemia virus-associated disorders. In nine cats, the cause of bilirubinuria was undiagnosed. Twenty-one (65.6%) of the 32 cats died or were euthanized as a result of the illness associated with bilirubinuria. Feline bilirubinuria detected by semiquantitative reagent tablet tests appeared to be an abnormal finding usually caused by liver disease. Recognition of bilirubinuria of any magnitude in cats should arouse a high index of suspicion for liver disease and might lead to a more accurate diagnosis for some cats with obscure illnesses.