A drug delivery device that utilizes a fluid subsystem with a switching device to deliver multiple drugs to an animal without causing contamination. The fluid subsystem can further comprise disposable syringes, fluid reservoirs, disposable tubing and a catheter. In the embodiments that utilize multiple disposable syringes, the drug delivery device allows a user to deliver multiple drugs to an animal through a catheter without contaminating the switching devices that control the flow of fluid. The drug delivery device can further utilize a controller to control the switching devices and a controller and syringe pumps to control the operation of the syringes.