Mowers are provided with a safety system to prevent obstacles, such as animals, located in the field from being hit by cutters of the mower. The safety system includes a control unit and at least one detector to detect the obstacle and then provide a warning signal to the control unit, when the obstacle is detected. The control unit provides a separation signal to at least one safety device in response to receiving the warning signal, and the at least one safety device causes separation between the obstacle and the at least one cutter in response to receiving the separation signal. The safety device may be at least one shield which is movable between a retracted position and a protecting position in which it extends in front of the at least one cutter to prevent contact between the at least one cutter and the obstacle.
