The renal mechanism for urate excretion in the Dalmatian coach-hound.

1. The renal mechanism for urate excretion in the Dalmatian dog resembles that in birds. Urate is cleared at a rate considerably greater than the glomerular filtration rate, indicating that its excretion is the result of both glomerular filtration and active tubular secretion. The basic physiological mechanisms involved in the anomalous purine metabolism of the Dalmatian are indicated and their possible biological significance briefly discussed. 2. A new enzymatic method for the direct estimation of true urate in biological fluids is described, which does not require the estimation of total urate and urate chromogen, followed by the calculation of true urate as a difference.