Preliminary necropsy results have found that Hani, one of two sister Siberian tigers brought to the Greater Vancouver Zoo in 2012, had pleuritis, a lung condition common in domestic cats.
Hani was found dead by zookeepers Wednesday.
Zoo manager Jody Henderson says the necropsy found that Hani exhibited changes in the chest compatible with pleuritis, an inflammation of the chest cavity and lungs.
She says the condition is not contagious and usually affects only one animal in a group.
She says the necropsy is not yet complete and further tests are being conducted to determine the cause of the pleuritis and whether the tiger's heart was also involved.
Henderson said Hani appeared to be healthy but became lethargic, was behaving abnormally and stopped eating the day before she died.
Hani and her sister, Hana, were born May 22, 2011, at Seoul Zoo in South Korea.
"Hani was the smaller of the two tigers and had a quiet demeanour when compared to her sister," Henderson said.
Hani died just 22 days before reaching her third birthday. It's the second Siberian tiger the zoo has lost in four months.
Sweetie, an 18-year-old Siberian tiger, was euthanized on Dec. 31, after suffering breathing problems, a loss of appetite and ongoing lethargy.
Henderson said the median life expectancy for female Siberian tigers in captivity is 14 years.
The zoo says the wild population of Siberian tigers is estimated to be between 400 and 500 animals, spread across areas of eastern Russia, China and North Korea.
The Greater Vancouver Zoo is located in Aldergrove, roughly 50 kilometres east of Vancouver.