A brake mechanism for a rope pulley of a leash. A rope is unwound from a pulley against the force of a spring and wound onto the pulley due to the force. The brake mechanism includes a brake button movable from an idle position, in which the pulley is freely rotatable, into a functional position, in which the brake button blocks unwinding of the rope. The brake button has an actuatable upper part protruding from the leash housing and a lower part cooperating with the pulley. The lower part is pivotable in the winding direction such that unwinding of the rope from the pulley is prevented, but can be wound onto the pulley in the functional position. The lower part engages brush bristles in the functional position to pivot the lower part due to pulley rotational movement in the winding direction.
