A trigger operated syringe (100) for intramammary injection of antibiotics has a fluid containing syringe cartridge (203) activated by a plunger (206) which is inserted into the syringe cartridge (203A) and expels fluid when the trigger (205) is pulled. A syringe cartridge holding mechanism (223) holds the syringe cartridge in place until the trigger (205) is released and the plunger (206) retracted. Single syringe cartridge (203) and multiple syringe cartridge (204) versions are disclosed. The plunger moves in a direction which is effectively perpendicular to the direction of movement of the trigger, allowing for ease of injection to a cow's teats, and ejection of the spent cartridges.