Elimination of salicylic acid in goats and cattle

Sodium salicylate was administered to cattle and goats IV and PO according to a crossover design. Total urinary excretion of SA and its metabolites was measured for 3 days after dosing. Salicyluric acid (SUA) was the only metabolite detected in urine of either species. Recovery of sodium salicylate and SUA in goats amounted to 67.9 and 34.6% of the dose, respectively, after IV administration. After oral dosing, total recoveries were 30.2% (sodium salicylate) and 71.7% (SUA) of dose. By comparison, cattle excreted significantly (P less than 0.05) less sodium salicylate (54.0%) and more SUA (49.9%) after IV dosing. The same pattern was observed after oral administration, wherein cattle excreted less than 12% as sodium salicylate and more than 99% as SUA. In both species, almost 90% of the drug excreted as sodium salicylate was found in urine within the first 12 hours after an IV dose and within 24 hours after oral dosing. The excretion of SUA was somewhat slower in both species, especially after oral administration. The data suggested that there were only quantitative differences in the metabolism and elimination of sodium salicylate between the 2 species, with cattle excreting a higher proportion of the drug as the glycine conjugate SUA.