Abstract: A system for monitoring animal body functions by analyzing the condition of the gas being breathed. A breathing tube, usually constituting a portion of anesthesia apparatus, contains sensing means in the form of a thermobead whose electric characteristics vary in accordance with temperature variations as heat is exchanged between the thermobead and the respiratory gas. Electronic analysis of the thermobead characteristics permits animal body functions such as breathing rate, breathing volume, animal body temperature and the like to be determined. Digital displays, recorders and alarms may be activated by the thermobead output.