An animal monitoring system, comprising: a bolus capable of oral administration to an animal, said bolus including: at least one bolus sensor capable of generating a bolus sensor signal which varies based on change in at least one physiological parameter of said animal; a bolus memory element; a bolus processor communicatively coupled to said memory element; a bolus computer code contained in said memory element executable to encode said at least one bolus sensor signal generated by said at least one bolus sensor; a bolus communication signal generator capable of generating a bolus communication signal carrying encoded bolus sensor data; and a bolus communication signal receiver; a tag securable to an external surface of said animal, said tag including: at least one tag sensor capable of generating a tag sensor signal which varies based on change in at least one environmental parameter surrounding said animal; a tag memory element; a tag processor communicatively coupled to said tag memory element; a tag computer code contained in said memory element executable to encode said at least one tag sensor signal generated by said at least one tag sensor; a tag first communication signal receiver capable of receiving said bolus communication signal carrying said encoded bolus sensor data; a tag first communication signal generator capable of generating a tag first communication signal at a tag first communication signal frequency relaying bolus programming data from a remote processor to said bolus communication signal receiver for reprograming said bolus computer code; and a tag second communication signal generator capable of generating a tag second communication signal at a tag second communication signal frequency carrying encoded environmental data or encoded bolus sensor data to the remote processor. a bolus capable of oral administration to an animal, said bolus including: at least one bolus sensor capable of generating a bolus sensor signal which varies based on change in at least one physiological parameter of said animal; a bolus memory element; a bolus processor communicatively coupled to said memory element; a bolus computer code contained in said memory element executable to encode said at least one bolus sensor signal generated by said at least one bolus sensor; a bolus communication signal generator capable of generating a bolus communication signal carrying encoded bolus sensor data; and a bolus communication signal receiver; at least one bolus sensor capable of generating a bolus sensor signal which varies based on change in at least one physiological parameter of said animal; a bolus memory element; a bolus processor communicatively coupled to said memory element; a bolus computer code contained in said memory element executable to encode said at least one bolus sensor signal generated by said at least one bolus sensor; a bolus communication signal generator capable of generating a bolus communication signal carrying encoded bolus sensor data; and a bolus communication signal receiver; a tag securable to an external surface of said animal, said tag including: at least one tag sensor capable of generating a tag sensor signal which varies based on change in at least one environmental parameter surrounding said animal; a tag memory element; a tag processor communicatively coupled to said tag memory element; a tag computer code contained in said memory element executable to encode said at least one tag sensor signal generated by said at least one tag sensor; a tag first communication signal receiver capable of receiving said bolus communication signal carrying said encoded bolus sensor data; a tag first communication signal generator capable of generating a tag first communication signal at a tag first communication signal frequency relaying bolus programming data from a remote processor to said bolus communication signal receiver for reprograming said bolus computer code; and a tag second communication signal generator capable of generating a tag second communication signal at a tag second communication signal frequency carrying encoded environmental data or encoded bolus sensor data to the remote processor. at least one tag sensor capable of generating a tag sensor signal which varies based on change in at least one environmental parameter surrounding said animal; a tag memory element; a tag processor communicatively coupled to said tag memory element; a tag computer code contained in said memory element executable to encode said at least one tag sensor signal generated by said at least one tag sensor; a tag first communication signal receiver capable of receiving said bolus communication signal carrying said encoded bolus sensor data; a tag first communication signal generator capable of generating a tag first communication signal at a tag first communication signal frequency relaying bolus programming data from a remote processor to said bolus communication signal receiver for reprograming said bolus computer code; and a tag second communication signal generator capable of generating a tag second communication signal at a tag second communication signal frequency carrying encoded environmental data or encoded bolus sensor data to the remote processor.