Abstract: A needle stick prevention device for a syringe. The syringe includes a barrel, a hub having a needle attached thereto, and a shoulder extending between the hub and barrel. A sleeve is slidably coupled to the syringe between a retracted position, in which the needle extends through an aperture in the top of the sleeve, and an extended position, in which the needle is housed within the sleeve. The sleeve has first and second slots cut into the sidewall. A retaining clip has first and second legs which are positioned in the first and second slots, respectively. The first and second legs exert a compressive force on the syringe barrel when the sleeve is in the retracted position to hold the sleeve in the retracted position. An upper stop extends radially outward from the hub. The first and second legs are biased inwardly between the upper stop and the shoulder when the sleeve is in the extended position to hold the sleeve in the extended position.

Abstract: A method and apparatus is disclosed for simultaneously injecting medication or vaccination fluid into animal tissue and permanently placing an electronic transponder therein. An ejector is formed by a hub, which is adapted to be secured to the syringe, and from which a sharpened, hollow needle projects. Inside the needle is an elongated rod which extends into the syringe so that actuation of the syringe plunger to flow liquid through the needle forces the rod towards the sharp end of the needle. The transponder is disposed proximate the sharp end of the needle so that the rod mechanically forces the transponder with the liquid into the tissue. A sleeve which engages the rod is disposed inside an enlarged chamber defined by the hub and can move a limited extent only over the length of the rod so that the transponder can be forced into the tissue while the rod is prevented from falling out of the needle in either direction.