Three rhesus macaques aged 20 to 28 retired from a laboratory to an Italian sanctuary in 2021. A new case study co-authored by Maria Padrell and Miquel Llorente shows that, even at that age, a simple feeding-enrichment programme left them more active and less stressed.
Every year, primates leave research laboratories at the end of their procedures, and a growing number get a second life in sanctuaries. But how do you help an animal recover after years in a barren cage? And is it still worth trying when it is old? Elderly individuals are often written off as too set in their ways to change.
“That assumption is exactly what we wanted to test,” says Miquel Llorente, researcher at the Comparative Minds Research Group of the Universitat de Girona and supervisor of the study. “If an old macaque can still change, retirement is not just a kinder ending: it is a real chance at a better life.”
The test came from three male rhesus macaques, aged 20, 20 and 28, who arrived in 2021 at the Animanatura Wild Sanctuary (Tuscany, Italy), run by LAV. Together with the sanctuary team, the researchers designed a simple, low-cost plan in three steps. First, six weeks of observation to see where the animals were starting from. Then six weeks with 14 sessions, each bringing a new kind of food-based enrichment. Finally, six weeks without enrichment, to check whether any change would last. Along the way, they recorded 131 hours of video and collected 137 faecal samples to measure cortisol, the stress hormone, without ever handling the animals.
“Behaviour tells you what an animal does; cortisol tells you how its body is coping,” explains Maria Padrell, co-author of the study and researcher in the same group. “Combining the two gives caretakers an objective way to know whether an intervention works, instead of relying on impressions.”
And it worked. Before enrichment, the macaques spent a quarter of their time resting and moved for only 7% of it. By the end, resting had nearly halved, to 13%, and movement had risen to 11%. Scratching and body-shaking, two behaviours linked to anxiety, became less frequent, and cortisol levels fell. Best of all, the improvements held once the enrichment was removed.
Llorente is careful about how far the results can go. “With three animals and no control group, this is a case study, not the final word, and part of the change may reflect settling into a new home,” he notes. “But the lesson for sanctuaries is easy to apply: measure first, enrich, and keep measuring. And age is no reason to give up on an animal.”
Reference: Dell'Anna, F., Albanese, V., Berardi, R., Kuan, M., Accorsi, P. A., Marliani, G., Padrell, M., & Llorente, M. (2026). Improving welfare through enrichment: A case study in aged ex-laboratory rhesus macaques. Animal Behaviour and Welfare Cases. https://doi.org/10.1079/abwcases.2026.0025
Funding: Spanish Ministry of Science and Innovation (PID2020-118419GB-I00; PLEISHOATA, PID2021-122355NB-C32) and LAV – Lega Anti Vivisezione. Miquel Llorente is a Serra Húnter Fellow (Generalitat de Catalunya).
Acknowledgements: The authors thank LAV ETS and the Animanatura Wild Sanctuary for making this research possible.