An apparatus (10) for discharging a dose of a fluid substance to an animal, the apparatus (10) including: a delivery assembly (12) adapted to discharge the dose of the substance to the animal and a control system (100) operatively associated with the delivery assembly (12) so as to selectively operate the delivery assembly (12), wherein the control system (100) is adapted to measure the discharge of the fluid substance from the delivery assembly (12) such that the dose is discharged when the delivery assembly (12) is operated.