Abstract: This study was conducted to determine the elimination of doxycycline hydrochloride tablets in lambs after administration according to the administration instructions and the withdrawal period. Doxycycline hydrochloride tablets were administered orally at 5 mg·kg^-1 of body weight, at an interval of 24 hours, for 5 consecutive doses. After the last administration, fat, muscle, liver and kidney were collected at 12 h, 1 d, 2 d, 3 d, 5 d, 7 d and 9 d respectively, and the content of doxycycline hydrochloride tablets in tissues was determined by HPLC-VWD. The linear range of doxycycline hydrochloride tablets in sheep fat, muscle, liver and kidney tissues is 50-5 000 ng·mL^-1. The linear equation and correlation coefficient are y=0.044x-0.414, R²=0.999. The results showed that doxycycline metabolism in lamb tissue was rapid. Nine days after the last administration, doxycycline was not detected in muscle, liver, kidney and fat. The lamb was given doxycycline hydrochloride tablets at 5 mg·kg^-1 body weight in this study. The withdrawal time was calculated according to the recommendations of the European Agency for the Evaluation of Medicinal Products (EMEA/CVMP/036/95) and was set at 2 days.

Key words: doxycycline, sheep, residue depletion, withdrawal time