Abstract: An automatic spraying device for farm animals, the device being comprised of a framework defining a passage through which farm animals are directed one-by-one. An electronic detection device is associated with the passage and connected to a control circuit to provide a detection signal thereto when a farm animal enters the passage. Spray nozzles are oriented with respect to the passage to spray animals passing through the passage. A pump is provided to supply a chemically treated liquid to the spray nozzles under pressure. The pump is actuated by the control circuit upon reception of the detection signal. One or more valves are connected to the spray nozzles and a liquid reservoir, containing the chemically treated liquid, is connected to the pump. A pump deactuation circuit including a timing circuit is provided to deactuate the pump after a predetermined time lapse after reception of a valve closing signal where the valve is closed to shut off the spray nozzles.