Animals conceal sickness in social situations
A review published this week has revealed that many animal species have the ability to conceal sickness in certain social situations, such as when there is a mating opportunity, or in the presence of young.
The review, titled “When is it socially acceptable to feel sick?”, examines a range of species including birds and primates, that conceal sickness in the presence of other animals.
There are a number of behaviours that are indicative of illness, and are common across a wide range of species. They include eating and drinking less, reduced activity and sleeping more to conserve energy.
The sole author of the review, Dr Patricia Lopes, is from the Institute of Evolutionary Biology and Environmental Studies at the University of Zurich. She reviewed a range of social situations that affected these sickness behaviours, including the presence of offspring, intruders or potential mates.
Dr Lopes says: “The idea is that behaving sick helps animals recover from the disease and so this should be the default way to behave when sick. 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.”
Dr Lopes continues by suggesting that feigning good health may have trade-offs for an animal with limited energy to invest in recovering from illness versus mating or caring for young.
An improved understanding of how the social situation affects the behaviour of a sick animal could improve models of disease detection and transmission, applicable to the spread of disease in humans living in an increasingly crowded world.
“Recognizing when animals are concealing their sickness is critical to how we both detect and control the spread of infectious diseases,” says Dr Lopes.
Over 60 per cent of communicable diseases in humans originate from animals, and the findings from this review could have implications in the context of infectious disease.
The Veterinary Medicines Directorate (VMD) is inviting applications from veterinary students to attend a one-week extramural studies (EMS) placement in July 2026.
