A system and method for tracking the health of a group of livestock. In an exemplary embodiment of the invention, the vital signs of a small number of sentinel animals is tracked and used to assess the existence and/or progress of a disease in the group. In an exemplary embodiment of the invention, the vital signs are assessed using a vitality sensor, for example, an accelerometer which provides signals indicating the type and/or other properties of movements made by the sentinel animals.
