The bulb of the syringe is designed to create suction when it is compressed and then released. To use the syringe, the user squeezes the bulb to expel any air and then places the tapered nozzle into the area to be suctioned. The user then releases the bulb, which creates suction and draws the fluid into the bulb.
 
Rubber suction bulb syringes are commonly used to clear mucus from the nose or mouth of pups, which can help relieve congestion and improve breathing.