Behavior of sick animals.

The behavior of the sick animal is not necessarily a result of physical debilitation; it can be viewed as part of a highly organized adaptive strategy that is at times critical to survival if the animal were living in the wild state. Domestic ruminants appear to have retained this behavioral mode when they are sick. This article brings together several lines of current research about depression, appetite control, and the role of fever in facilitating an animal's ability to combat viral and bacterial infections.