Occurrence of 5-hydroxy-3-indoleacetic acid in urine from several animal species.

1. The normal levels of 5-hydroxy-3-indoleacetic acid (5HIAA) were determined in the urine of four species of laboratory animals (dog, rabbit, rat and guinea-pig). 2. When 5HIAA excretion was calculated as mg/24 h, the output in the four species was in the order of rabbit greater than dog greater than guinea-pig greater than rat; but when it was calculated as mu/mg of creatinine, the order was guinea-pig greater than rabbit greater than rat greater than dog. 3. There were significant differences in the excretion of urinary 5HIAA between males and females within two species: rats and dogs.