This syringe is used in animal dentistry to inject a local anesthetic. The aspirating syringe differs from most syringes in that it is designed to inject anesthetic from a carpule. The parts of an aspirating syringe consist of a threaded tip where the needle attaches, a barrel where the carpule is placed, a piston rod(plunger) with a harpoon attached that embeds itself into the rubber stopper of the carpule, a finger grip, and a thumb ring.
The syringe allows the veterinarian to aspirate (draw back) the injection site to see if the needle tip is located in a blood vessel before injecting the anesthetic solution. Once the harpoon is engaged into the rubber stopper of the anesthetic carpule, the vetrenarian can apply inward or outward pressure on the stopper by exerting pressure on the thumb ring. Pulling the thumb ring outward also pulls the plunger outward producing an aspirating effect; whereas, pushing inward forces the anesthetic solution through the needle.