A lion at Scotland’s biggest safari park had to be destroyed after the pride leader bit though her spine.
Saskia, a 20-year-old lioness, died at Blair Drummond last month but details of the incident have only now emerged.
It is understood Saskia was attacked by a male member of the pride, suffering a horrific injury to her spine during the battle.
Vets who examined the lioness concluded there was no option but to humanely destroy her.
Animal rights campaigners said the incident showed that even the relatively large areas given to the lions at Blair Drummond were still too small to minimise the risk of deadly fighting between them.
In the wild, lionesses that refuse to breed with the dominant male can be killed or “banished”.
It is believed Saskia was bitten by nine-year-old male Zulu, who only joined the park in February from Emmen Zoo in the Netherlands.
A visitor to Blair Drummond spotted a zookeeper in a truck earlier this week chasing Zulu away from the four remaining females.
The zookeeper revealed: “He’s being kept away from the other lions because he’s being aggressive.
“A few weeks ago he bit through another lion’s spinal cord so it had to be put down.”
Park manager Gary Gilmour confirmed: “There was a lion that was bitten on the 6th June. She was put to sleep after a fight broke out with other lions. She had a wound on her back and would have been X-rayed when seen by the vet.”
Mr Gilmour added: “The lions all fight, including the females with each other, and it can be over anything.”
Animal campaigners People for the Ethical Treatment of Animals (PETA) said the incident could be the result of keeping the lions in relatively confined spaces.
PETA Director Mimi Bekhechi said: “While lions may attack one another in their natural habitats – they also have the opportunity to escape or to find a new territory, something denied to those kept in captivity.
“Lions are designed by nature to roam far and wide, hunt, claim territory, and seek out mates. In captivity, the average big cat enclosure is 18,000 times smaller than the animals’ natural roaming range.
“It’s impossible for these animals to express their instinctual desires and it should come as no surprise that they respond by showing neurotic or aggressive behaviour.”
Saskia’s death now leaves only four female lions at Blair Drummond – Libby, Karis, Teekay and Maklay – and one male, Zulu.
Earlier this year zookeepers were spotted around the park in tears after one of their two African elephants, Toto, had to be put to sleep.
The 46-year-old was a firm favourite and the park and left behind companion Modula – now the only remaining elephant left in Scotland.