“She seemed to be in significant pain,” Fleming said.
After a thorough health check under general anaesthesia, it became clear “something new had arisen that was complicating her already fragile health.
“After much discussion with the primate team, welfare committee and veterinarians,” the difficult decision was made.
She was euthanised on Wednesday.
A post-mortem examination should determine what caused Sally’s decline.
Primate Keeper Rowena Fraioli said the team will miss her “happy dance and beautiful vocalisations” that greeted them every day.
“She just loved people – children and older men particularly – she’d get extra excited if they had facial hair and would run over to see them,” she said.