An Asian elephant named Druk had to be euthanised at the Zurich Zoo on Tuesday, at the age of 49.
She had gone to sleep just before midnight on Monday, but was unable to get up the next day, a statement said.
Zookeepers gave the other elephants a chance to say goodbye to Druk, as the animals do in nature, before she was put to sleep.
At the end of 2014, vets determined that Druk was going blind. She suffered a fall in mid-April this year, and the zoo had to call firefighters and a crane to help get her up again.
Zoo director Alex Rübel had stated at the time that the elephant would be put to sleep if she started to suffer.
Druk was the oldest mammal at the Zurich Zoo. The elephant first arrived in Zurich as a gift from the king of Bhutan in 1968, when she was just 15 months old. She never had offspring of her own, but helped to raise a dozen fellow elephants.
swissinfo.ch and agencies