Summary
Mechanisms to maintain the physiological and behavioural stability of animals during long distance transport are explored according to the epidemiological concept of the risk factor. The purpose is to consider quality assurance and risk management as two practical means of protecting animal health and welfare during long distance transport. The hierarchy of welfare, health and disease is treated as an indivisible whole to ensure that surveillance for welfare will encompass surveillance for infectious disease and that ethical consideration applies to the totality. Disease can have devastating effects on the well-being of both animals and people. Risk factors and epidemiological methods are explained and promoted for use in managing the health and welfare of animals transported over long distances. A 'one medicine' approach is emphasised and the depiction of stress as the cost of adaptation to stressors or the allostatic load is introduced to illuminate the challenges confronting transported animals. Aspects of heat stress in cattle are explored to illustrate how various sources of information, including inference from general biological knowledge, can assist in characterising risk factors that derive from the constitution of animals themselves.