A system and apparatus to track and control an animal is described, including a tracking unit to track the animal, and a stimulus unit to provide a stimulus to the animal, wherein the tracking unit and stimulus unit are configured to be coupled together. The stimulus unit is entirely a slave device to the tracking unit and has no independent smart circuitry, no independent power supply and no antennae. Accordingly, the stimulation unit is dependent upon the tracking unit for operation, power and for communication to and from a remote hand held control device.