Cattle can have a fever up to 72 hours before showing visual signs of illness. With the Fever-Sensing Ear Tag (called a FeverTag), a sick animal can be detected-and treated-sooner than that. While it looks like a typical ID tag, the tag contains a computer microprocessor that automatically monitors an animal's body temperature every 15 minutes. If that temperature exceeds 103 degrees, the tag begins to flash brightly for six hours straight, sufficient to make sure one is aware that an episode has occurred. A FeverTag will last a minimum of 180 days before having to be replaced.