A drench gun (10) for discharging a dose of a fluid substance or medicament to an animal is described. The gun is hand held and driven by a portable pressurised gas canister or vessel (65). It includes a sensor for measuring the amount of drench (34) and a control valve (67) for controlling the amount distributed. The device optionally includes an identification device (84) that can read an RFID or other antenna attach to the animal to decide how much medicament is to be delivered, based on weight or age.
