Surgeons perform first reported mastoidectomy on a gorilla at San Diego Zoo Safari Park

A 12-year-old male western lowland gorilla at the San Diego Zoo Safari Park in California has undergone what is believed to be the first mastoidectomy ever reported in a gorilla, a procedure his care team used to treat an infection that had spread into portions of his skull.

The gorilla, named Mizani, was treated by a multidisciplinary team combining wildlife health experts from the Safari Park with surgeons from UC San Diego Health. The operation took place at the park's Harter Veterinary Medical Center.

A CT scan at the Harter Center revealed that Mizani had sinusitis and mastoiditis, an infection of the large bone behind the ear that occurs in both humans and gorillas. The diagnosis followed several changes first noted by wildlife care specialists in March 2026, including a reduced appetite and reluctance to fully open his mouth. Specialists also observed Mizani holding his head and squinting, which were consistent with head pain. Because the disease was already extensive when diagnosed, wildlife health experts suspect it began before Mizani arrived at the Safari Park in November 2024.

Two clinicians from UC San Diego Health, otolaryngologist Jeffrey Harris, MD, PhD; and resident fellow Krish Suresh, MD, resident fellow at UC San Diego Health, played central roles in the procedure. The surgeons were able to borrow approaches from human skull base and ear surgery, as humans and gorillas share similar anatomies. Still, those similarities did not eliminate important differences that posed challenges during the surgery, and with no documented cases of the procedure in gorillas, the team proceeded cautiously.

"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 in a news release by San Diego Zoo Wildlife Alliance.¹ "After carefully analyzing CT scans, we adapted our approach to account for the significant anatomical differences and proceeded with delicate microsurgery."

Although the San Diego Zoo Wildlife Alliance frequently works with human health care specialists on complex cases, the team believes this was the first reported mastoidectomy performed on a gorilla anywhere in the world. Surgeons made an incision along the left side of Mizani's head to access and drain the infected area, then removed portions of the infected mastoid bone and tissue before closing the surgical site.

The operation lasted about 5 hours from anesthesia induction through recovery and involved more than 20 veterinarians, physicians, registered veterinary technicians, wildlife care specialists, and support staff from both organizations.

Ryan Sadler, DVM, senior veterinarian at the San Diego Animal Sanctuary, said the disease is rarely seen in gorillas, making the case a learning opportunity for the team. "Even after working with gorillas throughout my career, I'm still learning something new every day. Procedures like this highlight how medicine can be remarkably similar across species, while also requiring very different approaches depending on the animal," he said.¹

Mizani has continued to recover well. A recheck exam in early June showed significant improvement with no indication of complications, and the procedure appears to have resolved his condition. He is scheduled for another recheck in 1 year unless clinical signs arise. He has returned to his troop and resumed his normal diet, activity level, and daily routine.

The case coincides with the 25th anniversary of the Harter Veterinary Medical Center, which opened in 2001 and has since cared for more than 50,000 animals representing hundreds of species.

Reference

1. First-of-its-kind surgery performed on western lowland gorilla at the San Diego Zoo Safari Park. News release. San Diego Zoo Wildlife Alliance. July 13, 2026. Accessed July 15, 2026. https://prnmedia.prnewswire.com/news-releases/first-of-its-kind-surgery-performed-on-western-lowland-gorilla-at-the-san-diego-zoo-safari-park-302822563.html