* A microchip implant is an identifying integrated circuit placed under the skin of an animal. The chip, about the size of a large grain of rice, uses passiveRFID (Radio Frequency Identification) technology, and is also known as a PIT tag (for Passive Integrated Transponder) . * Externally attached microchips such as RFID ear tags are commonly used to identify farm and ranch animals other than horses. Some external microchips can be read with the same scanner used with implanted chips.