Groundbreaking Mastoidectomy Saves San Diego Zoo Gorilla Mizani

On March 26, 2024, Mizani, a 12-year-old male western lowland gorilla at the San Diego Zoo Safari Park, underwent a mastoidectomy—the first documented surgery of its kind on a gorilla. UC San Diego Health otolaryngologists Dr. Jeffrey Harris and Dr. Krish Suresh performed the five-hour procedure at the park’s Harter Veterinary Medical Center, removing infected mastoid bone and tissue that had caused sinusitis and mastoiditis. More than 20 veterinarians, physicians, technicians and wildlife specialists collaborated on the operation.

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Mizani first exhibited head pain, reduced appetite and reluctance to open his mouth in early March. A CT scan confirmed chronic infection of the mastoid bone behind his ear—a condition rare in gorillas but analogous to human mastoiditis. Initial treatment with anti-nausea medication and a non-steroidal anti-inflammatory drug failed to resolve symptoms, prompting the decision for surgical intervention. The team adapted human skull-base techniques to accommodate the gorilla’s distinct anatomy, making an incision along the left side of his head, draining the infection, excising diseased bone, and closing the site. Post-operative monitoring showed no complications, and a June recheck indicated “significant improvement.”

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San Diego Zoo Wildlife Alliance officials reported that Mizani has returned to his troop, resumed normal diet and activity, and will receive a follow-up exam in a year unless clinical signs reappear. Senior veterinarian Ryan Sadler emphasized the collaborative effort between zoo staff and UC San Diego surgeons, noting the case’s value as a learning opportunity for both veterinary and human medicine. UC San Diego Health highlighted the successful adaptation of complex mastoid and skull-base expertise to a non-human patient.

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• “Our surgical team regularly performs complex mastoid and skull base procedures but applying that expertise to a critically ill gorilla required meticulous planning,” — Dr. Jeffrey Harris, Otolaryngologist-Head and Neck Surgeon

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• “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.” — Dr. Jeffrey Harris

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• “This case was particularly unique because this disease is rarely seen in gorillas, making it a valuable learning opportunity for everyone involved,” — Ryan Sadler, Senior Veterinarian, San Diego Zoo Safari Park

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• “Even after working with gorillas throughout my career, I'm still learning something new every day.” — Ryan Sadler

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• “This case was interesting because it was relatively unusual and unique,” — Ryan Sadler

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The successful mastoidectomy demonstrates that advanced human surgical techniques can be safely translated to endangered wildlife, expanding treatment options for species with limited veterinary precedents and reinforcing interdisciplinary collaboration between human and animal health professionals.

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