Auckland Zoo has made the difficult decision to put down one of its old Sumatran tigers, Molek yesterday.
Molek, which means beautiful in Malay, was born in January 2000 and had begun slowing down as she aged but keepers noticed a sudden change in her movement and appetite in recent days.
Senior vet An Pas said the decision was made to put her under to perform a full inspection.
"Taking into consideration the results from this procedure, which showed declining age-related health issues, along with the rapid deterioration of her general demeanour, putting her to sleep was absolutely the right and kindest decision to make," she said.
A post mortem will be performed to establish what caused Molek's decline.
Lauren Booth, the team leader of carnivores, said there was a feeling of disbelief that the old Tigress had gone.
"She has left us with some exceptional memories from over the years which we will all cherish, one of my favourites is of the day we first found out she had given birth to three healthy cubs."
Molek lived at three of New Zealand's zoos after being born in Wellington before living in Hamilton from 2001 to 2006, when she was then moved up to Auckland.
She made Auckland Zoo history in 2008 when she gave birth to its first three tiger cubs, Jalur, Berani and Cinta.
There are less than 400 Sumatran tigers in the wild.