Abstract: The present invention provides a bolus for introducing into a ruminant animal's reticulum, comprising at least one pressure sensor (e.g. acoustic sensor and pressure transducer) configured and operable for receiving an overall pressure signal emanated by two or more signal sources in its surroundings and outputting a data stream indicative thereof; a processing utility for receiving and processing the data stream indicative of the overall pressure signal to isolate therefrom signal components from two or more defined sources and outputting one or more values indicative of a health condition of the animal; and a communication utility for receiving said one or more values and transmitting a signal corresponding thereto. The invention also provides a method for monitoring health condition of a ruminant animal and a system therefore, making use of the bolus of the invention.