A retention box for use in feeding or examining a domestic animal, particularly a sow, is designed in a known way with a frame (5) which at one end is provided with a feeding trough (7) and at the other end with an access opening for the sow. The box is provided with a pivotable front gate (9) and a pivotable rear gate (11) which are rigidly interconnected by rods (13). By opening the rear gate (11), the front gate (9) is forced into closed position, and vice versa. In order to avoid unsuitable oscillations in the closure system and thereby problems with getting the sow out of the box again, the connection between front and rear gates is provided with a locking device which may release the rods (13) such that the movements of the gates are not mutually dependent. By the invention, the rods are seated in bushings (21) that allow sliding movement of the rods (13) in relation to the adjacent gate (11). By manually operated locking pins (25), the rear gate (11) may be locked in the open position such that the animal may come out.