A hoof trimming stall has a front gate having two pivotally mounted spaced-apart doors for swinging inwardly and outwardly. The doors are movable between a catching position in which the doors point inwardly for receiving a head of the animal entering the stall, a closed position for holding the animal in the stall with the neck of the animal caught in a gap between the doors, and an open position in which the doors point outwardly for permitting the animal to exit. A door lock/release mechanism has a slider arm movable forward and backward, a hydraulic cylinder for moving the slider arm forward and backward, a rear catcher mounted on the slider arm for preventing the doors from moving from the closed position to the catching position, a front catcher mounted on the slider arm for preventing the doors from being opened by the animal when the doors are in the closed position, and a release mechanism for permitting the doors to move from the open position to the catching position. An automatic reset mechanism automatically resets the doors and door/lock release mechanism. The reset mechanism has a sensor for signaling the hydraulic cylinder to move the slider arm backwards when the doors are in the open position and a spring for biasing the doors from the open position to the catching position.