One has a very hard time persuading a vet that animal disease is not an important phenomenon of veterinary science that also has financial implications, but is fundamentally an economic problem that has some veterinary science aspects (McInerney, 1996, p.301). The existence of diseases of agricultural animals impose costs on communities, either as costs of the disease or as costs of avoiding the costs of the disease. In this paper, the focus is on economic ways of thinking about the health of agricultural animals. In part one, the essence of economic approaches to analysis of problems is outlined. Then in part two a common method of analysing the costs and benefits of reducing or preventing agricultural animal disease is shown, and the flaws highlighted. In part three useful economic ways of thinking about the costs and benefits associated with animal disease and its prevention and reduction are explained.