The level of urine cortisol and creatinine is used for screening of hyperadrenocorticism, however, there was only few information concerning the effect of sex hormone on level of urinary cortisol and creatinine in dogs. The aim of this study was to investigate the level of urine cortisol and creatinine in intact male and neutered dogs and provide the optimal time of urine collection for screening of hyperadrenocorticism in dogs. The urine cortisol concentration in the intact group was significantly higher than the neutered one at 8:00 (P<0.05). In the intact group, urinary creatinine was decreasing from 8:00 to 16:00 of three consecutive days, though there was no statistical difference between each time. Urine creatinine was ascending in the neutered group from 8:00 to 16:00 with no significant difference at each time. In addition, the urinary creatinine concentration of neutered group was significantly higher than intact group at 16:00 (P<0.05). For the total mean urinary cortisol and creatinine ratios (UCCRs) of three consecutive days, intact group was significantly higher than the neutered group (P<0.05). There was no significant difference of UCCRs between neutered group and intact group at 8:00, while the UCCRs of intact group was significant higher than the neutered group at 12:00 and 16:00 (P<0.05). UCCR was significantly positive linear correlated to urine cortisol (r=0.568, P<0.001) but significantly negative linear correlated to creatinine (r=-0.5009, P<0.001). Thus, we can recommend that the optimal time of urine collection for UCCR was at 8:00 in the morning.

Key words: Cortisol, Creatinine, UCCR, Urine