The Macaques

In 2017, four male macaques joined the primate enclosure at the Institute of Neuroinformatics of the University of Zurich and the ETH Zurich. One of the monkeys had to be put down due to health reasons in January 2022.

Macaques (Macaca mulatta) are gregarious animals. The four macaque males at the Institute of Neuroinformatics grew up together and formed a social group. Their names are Charles, Max and Paul. Alan, the fourth member of the group, had to be put down on 13 January 2022. He had developed health problems (diarrhea) from November 2021 onward and continuously lost weight. In the same month, Alan suffered a severe intestinal infection and had to undergo an emergency procedure and several weeks of medical treatment.

His health temporarily returned to normal for the most part but deteriorated again in January. Despite several diagnostic examinations under anesthesia, the reasons for his illness could not be determined. It is presumed that Alan suffered from an infection that could not be treated despite medication.

With no prospect of improving the monkey’s health, the study director, in consultation with the responsible veterinarian, decided to euthanize Alan before he had to suffer – a decision taken in the interest of animal welfare. The autopsy that was subsequently performed did not lead to a definitive diagnosis. There were no indications that Alan's health problems were related to the experiments.

For most of the day, the animals are not engaged in experimental work, but rather live and interact with their own kind in the primate enclosure. The macaque enclosure measures 23 square meters, is over three meters high, and provides the animals free access to a 34-square-meter outdoor enclosure. The overall enclosure covers 171 m³ of space and gives the animals opportunities to play, climb and even retreat indoors and outdoors. To create conditions the animals would meet in their natural environment, part of their food is hidden, ensuring they have to go in search of it.