Abstract: A diagnostic and therapeutic instrument for use in the treatment of living organisms is provided including a sensor for detecting magnetic fields emanating from the living organism. The sensor is located proximate to the organism and is formed from a ferromagnetic core surrounded by a multi-turn fine wire coil. The sensor is coupled to signal processing which amplifies a signal from the sensor and filters out portions of the signal which represent background magnetic fields emanating from other sources. The signal from the sensor is utilizable to detect abnormalities in the field emanating from the organism indicative of the organism's well-being. The signal can also be utilized to excite a magnetic field radiator which outputs a field complementary to the field emanating from the organism.