One of the Calgary’ Zoo’s western lowland gorillas has undergone emergency surgery after caregivers noticed unusual changes to her behaviour and appetite.

Calgary Zoo officials say Zuri, a 19-year-old female, underwent advanced tests on Wednesday. She was diagnosed with a severe abdominal infection and the zoo’s veterinary team performed an emergency surgical procedure.

Zuri remains in a compromised state and her condition is considered critical. The Calgary Zoo’s animal care team continues to monitor Zuri’s recovery.

The Calgary Zoo is home to a five member gorilla troop consisting of 37-year-old Kakinga, 19-year-old Zuri, 18-year-old Kioja, 15-year-old Dossi and a baby gorilla born on March 9, 2016/