Reliability of taurine concentrations measured in single urine samples obtained from dogs eight hours after eating

Objective - To evaluate the reliability of taurine concentrations measured in a single urine sample obtained from dogs 8 hours after eating, compared with taurine concentrations measured in 24-hour urine samples. Animals - 18 healthy Beagles. Procedure - After emptying the urinary bladder by transurethral catheterization, dogs were fed a canned maintenance diet. Approximately 8 hours later, urine, plasma, and serum samples were obtained for determination of fractional urinary excretion of taurine and urine taurine-to-creatinine concentration ratios (U_taur:U_cr). Results were compared with 24-hour urinary taurine excretion rate. Results - Unbound and total fractional urinary taurine excretion correlated well with unbound and total 24-hour urinary taurine excretion. However, bound fractional urinary taurine excretion correlated poorly with bound 24-hour urinary taurine excretion. Unbound and total U_taur:U_cr, correlated well with unbound and total 24-hour urinary taurine excretion. However, bound U_taur:U_cr correlated poorly with bound 24-hour urinary taurine excretion. Conclusion and Clinical Relevance - Fractional urinary excretion of unbound and total taurine, and unbound and total U_taur:U_cr are reliable indicators of 24-hour urinary unbound and total taurine excretion in healthy dogs. However, determination of 24-hour urinary taurine excretion is recommended for evaluating urinary bound taurine concentrations of dogs. (Am J Vet Res 1999;60:186-189).