Stress in the period during transport and around slaughter is known to influence the physiological and biochemical processes in pigs. Pigs that become unable to walk without obvious injury, trauma or disease are considered fatigued. Fatigued pigs tend to be of heavy muscled, high lean genetic types. Visual indicators of a stressed pig include open mouth breathing, muscle tremors, downed pigs, reddened areas of the skin, and increased body temperature. Within North America, normal appearing market-ready swine continue to die in transit or in a pen. Animal factors that could influence stress include the social environment (crowding, aggression, hierarchy, etc.), genetics, fear (characterized by a high pitched vocalization), exposure to handling (more exposure to handling by humans will result in less stress), nutrition (fasting prior to shipment will increase aggression and stress), health, facilities (pigs can wedge themselves in narrow corridors), and goading methods (do NOT use a prod). Human factors that could influence stress include the role of the handler (attitude of the handler and behaviour of the handler in regards to moving pigs) and role of training (be sure to not move more than 5 or 6 at a time and do not panic a fall-behind pig).