Pig. Thermogram of a domestic pig (Sus scrofa domestica). A thermogram shows variation in temperature on the surface of an object, measured by the long-wave infrared radiation it emits. The temperature scale is colour-coded and runs from white (0.9 degrees Celsius, coldest) through yellow and red to dark blue (warmest, 38 degrees Celsius). A pig has fat deposits in and beneath its skin which help to insulate it from the cold.