Animals Conceal Their Sickness In Certain Social Situations

Animals have the ability to conceal their sickness depending on the social situation, according to a recent study.

When they are sick, animals from a number of different species will eat and drink less, reduce their activity and sleep more in order to conserve energy for their recovery. However, researchers from the University of Zurich in Switzerland found that this can all change when animals are given the opportunity to mate or are in the presence of their young.

"The idea is that behaving sick helps animals recover from the disease and so this should be the default way to behave when sick," Patricia Lopes from the Institute of Evolutionary Biology and Environmental Studies at the University of Zurich said in a statement. "However, if being sick coincides with, for example, a unique opportunity to mate, then animals may adjust their priorities and behave as though they are not sick."

Lopes said that such a change may have tradeoffs for an animal with limited energy to invest in recovering from illness versus mating or caring for young.

For the study, Lopes reviewed a range of different social situations that affected the behavior of sick animals, including the presence of offspring, intruders or potential mates.

Their findings showed that animals ranging from birds to monkeys have all been demonstrated to conceal their sickness behavior when other animals are present.

The review, which was recently published in the journal Proceedings of the Royal Society B, also considers the implications in the context of infectious disease.

"Recognizing when animals are concealing their sickness is critical to how we both detect and control the spread of infectious diseases," Lopes said.

She said improving the understanding of how the social situation affects a sick animal's behavior can improve current models of disease detection and transmission. This also extends to the spread of disease in humans living in an increasingly crowded and connected world as more than 60 percent of communicable diseases in humans originate from animals, according to the U.S. Center for Disease Control.