Changes in behavior have for thousands of years been recognized as a sign of illness in animals; anorexia for example is frequently observed. In the last decade there has been a tremendous increase in research exploring the relationships between behavior and disease in part due to the development of a new conceptual perspective. It was long believed that changes in the behavior of sick animals was simply the result of the debilitating effects of the illness; for example, intake declines because an animal lacks the energy required to forage or compete for access to food. However, Hart (1988) and others (Danzer, 2004) have argued that many of the behaviors shown by ill animals are part of a coordinated strategy to fight illness. Behavior is an important means of influencing energy expenditure. Sick individuals may be highly motivated to decrease feeding time and increased time at rest as a means of conserving energy for responses of critical short-term value like mounting an immune response to fightan infection (Hart, 1988) . With this new conceptual framework in mind it opens the door to considering the management of sick animals in a different light.
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