Perth Zoo's only male lion has tragically died during a routine dental surgery.
Mandela, who was 14 years old, died suddenly from heart failure as he was having dental surgery to remove two fractured teeth on Tuesday.
The West Australian zoo said veterinarians did everything they could to revive the lion, but could not save him in the end.
Perth Zoo spokesperson Danielle Henry told WA Today it was a textbook procedure but Mandela went into heart failure right towards the end.
She said vets performed CPR on Mandela and managed to revive him twice.
But on the third time, Ms Henry said Mandela crashed again and they were not able to bring him back. 'It definitely wasn't something we were expecting and it was quite sudden,' she said.
Ms Henry said Mandela was part of the family at Perth Zoo and staff were left shattered.
'We've cared for him since 2007 and our staff are absolutely devastated,' she said.
The loss of Mandela was felt particularly hard because he was the only male lion left, after his brother Nelson succumbed to pneumonia in April 2016.
Both lions were taken to Perth Zoo's Savannah in 2007 and were 14-years-old when they died.
After his passing, Mandela was described by the zoo as a dominant male 'with the battle scars to show for it'.
While the loss of both its male lions this year rocked the zoo, Perth Zoo said it still had a lioness, Shinyanga, who was born in 1999 and had lived at the zoo since 2012.
Senior veterinarian Simone Vitali said Mandela was a very sociable animal who captured the hearts of people who both worked at and visited the zoo.
'The loss of Mandela within the same year (as Nelson's death) is a real blow for everyone ... a total shock for everybody,' Ms Vitali told ABC News.
'Everybody is trying to deal with that now and go through their processes and get support from one another.'
Ms Vitali said the dental procedure was very routine for the zoo and there were no signs leading up to his cardiac arrest that would suggest anything was wrong.
She said the anesthetic was running routinely, and his health was in good condition right up until he stopped breathing and his heart stopped beating.
The zoo said it was now in the process of conducting an autopsy on Mandela to discover what caused his heart to give way.
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