Hani, the two-year-old Siberian tiger, that died unexpectedly at the Greater Vancouver Zoo on Thursday suffered from pleuritis, according to the preliminary necropsy results.
Pleuritis is an inflammatory process involving the lining of the chest cavity and lungs.
A veterinary pathologist confirmed Hani exhibited changes in the chest compatible with the condition.
The condition was associated with circulatory changes in the lung and partial collapse of the lung.
Pleuritis is a fairly common problem in domestic cats and is usually a sporadic, non contagious disease affecting one animal in a group.
More tests are needed to determine what caused the pleuritis and whether there might might have been any heart problems.
The day before she died, Hani appeared healthy although she had been abnormally off her food for a day, lethargic and her behaviour was off.
She was almost three years old. The median life expectancy for a female Siberian tiger in captivity is 14 years.
Hani was born at a zoo in South Korea in May of 2011.
She arrived at the Greater Vancouver Zoo with her sister, Hana, in June of 2012.
Hani was in the same enclosure with her sister when she died.
A final necropsy report is expected by the end of next week.