Body temperature has long been recognised as a vital sign in both people and animals. Although fever and chills have been ascribed to pathological processes since Hippocrates, at that time only the hands were used to detect changes in the temperature of the human body. In 1592, a crude temperature measuring apparatus was invented by Galileo Galilei and the documentation of body temperature began. That instrument, however, did not allow quantitative readings to be obtained as it lacked a scale. The introduction of a scale was first seen when Santorio conceived a mouth thermoscope, introduced in his 1612 work entitled Sanctorii Sanctorii Commentaria in Artem medicinalem Galeni (Pearce 2002, Kelly 2010). Several new techniques have been introduced into medical practice since then and technology has been largely incorporated into diagnostic procedures. Nevertheless, in spite of modern blood tests, molecular analyses, CT scans, MRI scans, and many other ancillary methods, physical examination remains the cornerstone of medical practice, allowing assessment of a patient's vital signs and the identification of abnormal characteristics. As part of a physical examination, body temperature measurement may document variations in core temperature that might be associated with many medical conditions. Although fairly simple, measuring body temperature requires a consistent, precise and reproducible method of acquisition in clinical practice. Ideally, temperature would be acquired at the hypothalamus level or at the thermoregulation centre, but, needless to say, those sites are not suitable in a clinical setting. Indeed, the rectal mucosa is still recognised as the 'gold standard' for assessing body