Preliminary post-mortem report of the male tiger – ST-16 – that died on Saturday at the Sariska Tiger Reserve in Alwar district of Rajasthan indicated that the possible cause could be heatstroke, The Times of India reported. A tumour on its leg must have weakened the big cat.

The post-mortem of the tiger was conducted on Sunday by experts from Indian Veterinary Research Institute in Bareilly, National Tiger Conservation Authority, Wildlife Institute of India and other local staff.

“The autopsy revealed that the tiger had a tumour on its leg which had reached its bones,” Chief Wildlife Warden Arindam Tomar told The Times of India. “While heatstroke seems to be the cause of death according to the initial reports, the tumour could have also weakened the animal, because of which it was unable to take the heat.”

Tomar said a detailed autopsy report will reveal if the tumour was cancerous. “If that reveals something untoward, then action will be taken accordingly,” he added. It will also reveal other details like when did the animal eat and drink last, said Dr Arvind Mathur, who had treated the tiger who was given a tranquiliser after he was limping. The final autopsy report is expected in a couple of days.

Refuting initial reports that said that the tiger might have succumbed to an overdose of tranquiliser, Tomar said: “The animal was tranquilised in the morning when the temperature was not very high and it was revived as well. The tiger died few hours after the medical treatment was administered. It collapsed very close to a water hole.”

The tiger was tranquilised around 7.15 am on Saturday and revived around 9 am. The time of death is estimated to be 1 pm.

However, wildlife conservationist said the death of the tiger could have been avoided had it not been released into the wild soon after treatment. “This death is very unfortunate but could have been prevented if the medical team had released the tiger when the temperature was cooler,” said Simrat Sandhu, a wildlife conservationist. “There are ways and means to keep the tiger restrained and cool till the time it had fully recovered from the effects of tranquiliser.”

The tiger was brought from Ranthambhore National Park in Sawai Madhopur to Sariska in April. With the death, there is one male tiger for eight tigresses in Sariska, according to India Today. Before this, Sariska lost two male and one female tigers and at least three cubs in less than two years.