A 44-year-old female gorilla from the Toronto Zoo is recovering after surgery to remove a mass from her leg.

Medical staff from Toronto’s Scarborough Hospital performed the surgery on Tuesday in the western lowland gorilla habitat at the zoo.

The zoo said Wednesday in a release that a large mass in Josephine’s left leg area was affecting her ability to walk so veterinarians approached the hospital’s general surgery division to discuss options.

The mass turned out to be a slow-growing, fatty lump underneath the skin, and it was determined Josephine’s ability to walk normally was also related to arthritis, which was investigated while she was under anesthetic.

Dr. Saul Mandelbaum says the surgery went very well and Josephine is “recovering nicely.”

The zoo’s wildlife health centre and wildlife care team are monitoring Josephine while she recovers.

“We wanted the best care for Josephine, who is an older gorilla, which is why we approached Dr. Mandelbaum, who performs inguinal hernia surgeries on a regular basis, often in elderly patients,” said Dr. Chris Dutton, head of veterinary services at the Toronto Zoo.

Josephine arrived at the Toronto Zoo from Gabon, West Africa, on May 9, 1974, before the Zoo opened in August.

She has given birth to five offspring while at the Toronto Zoo, four of which were sired by Charles. She is now grandmother to five gorillas at zoos throughout North America.

The Toronto Zoo is a member of the North American Gorilla Species Survival Plan, which focuses on maintaining a genetically and demographically healthy zoo gorilla population and conservation efforts to protect them in the wild.