Abstract: An animal identification and medication syringe includes a barrel, a plunger piston which moves longitudinally within the barrel in response to air pressure within the barrel, and a syringe needle for penetrating the hide of an animal and for introducing medication into the animal. A valve mechanism or plug assembly enables the syringe to selectively deliver medication into the animal. The plunger piston evacuates the medication chamber within the barrel, and also acts as the force by which the syringe is ultimately ejected from the animal after medication has been delivered. A marking disk may be mounted on the distal end of the syringe to disinfect the needle and/or to mark the animal upon impact of the syringe with the animal. A rapid refill device is also provided to refill the syringe numerous times without having to disassemble or otherwise manipulate the syringe.