A 12-year-old male western lowland gorilla living at the San Diego Zoo Safari Park underwent what is believed to be a first-of- its-kind surgery by UC San Diego Health physicians and is recovering well.

The Safari Park’s Harter Veterinary Medical Center performed a CT scan on Mizani the gorilla, confirming he had sinusitis and mastoiditis, an infection of the large bone behind the ear that can occur in both humans and gorillas.

Veterinarians and wildlife care specialists noticed in March that Mizani was “reluctant to open his mouth fully, had a decreased appetite, and was exhibiting behaviors often associated with head pain, like holding his head while squinting his eyes,” according to a statement from the San Diego Zoo Wildlife Alliance.

Following the CT scan, doctors believe he had developed the condition before he arrived at the Wildlife Park in November 2024.

Dr. Jeffrey Harris, an otolaryngologist-head and neck surgeon, and Dr. Krish Suresh, a resident fellow at UC San Diego Health, played a critical role in adapting human techniques to Mizani’s skull. Humans and gorillas share many similarities anatomically, but differ in key ways.

“Our surgical team regularly performs complex mastoid and skull base procedures but applying that expertise to a critically ill gorilla required meticulous planning,” Harris said. “After carefully analyzing CT scans, we adapted our approach to account for the significant anatomical differences and proceeded with delicate microsurgery. We’re proud to bring this level of specialized care beyond the traditional clinical setting and we are incredibly gratified by Mizani’s recovery.”

The Wildlife Alliance could not find any literature detailing a mastoidectomy ever being performed on a gorilla, leading park leaders to believe this was a world first.

According to the doctors, the surgery involved making an incision along the left side of Mizani’s head to access and drain the infected area, followed by removal of portions of infected mastoid bone and tissue and careful closure of the surgical site.