California Academy of Sciences’ Innovative Tendon Surgery on African Penguin Chick Published in Journal of Zoo and Wildlife Medicine

San Francisco, CA (June 17, 2025) — In a groundbreaking step for avian veterinary medicine, the California Academy of Sciences has successfully performed a novel tendon stabilization surgery on a young African penguin (Spheniscus demersus) involving re-aligning the compromised tendon with a screw and washer, marking the first known instance of success in a bird with this specific surgical technique. The procedure and its outcome are the subject of a scientific paper published in the Journal of Zoo and Wildlife Medicine today.

The patient, a juvenile African penguin named Ignatz (“Iggie”), is a member of the Academy’s beloved colony of African penguins—a critically endangered species. Iggie was hatched as part of a penguin baby boom at the Academy under the AZA Species Survival Plan (SSP) to maintain genetic diversity in the species. However, at just 60 days old, Iggie developed a condition known as perosis, in which the gastrocnemius tendon (analogous to the human Achilles tendon) slips out of its natural groove at the ankle, or “hock” joint in birds. This displacement prevents the bird from fully extending its foot, making it difficult or impossible to walk. Perosis has long presented significant challenges for zoo and aquarium professionals caring for penguins and other birds with similar anatomy, although the underlying cause of this condition is currently unknown.

“Perosis has historically been very difficult to treat in penguins, especially in chicks,” said Dr. Freeland Dunker, recently retired senior veterinarian at the Academy. “Previous approaches, ranging from physical therapy to custom footwear and even amputation, have had mixed results—and in some cases, have required euthanization of a bird, a big loss considering the species’ very delicate status. Iggie’s case offered us a chance to try a modification of previous attempts, and we’re thrilled with the outcome.”

The Road to Repair

At first, Academy biologists fitted Iggie with a custom-made boot designed by Teva to support his range of motion and keep the tendon in place. While this approach worked initially, the tendon would still intermittently slip in and out of place. The team then elected to repair the tendon surgically.

The Academy’s in-house veterinarians Drs. Lana Krol and Freeland Dunker, DVM, CertAqV, consulted extensively with the AZA African Penguin SSP veterinary advisory team, as well as veterinary staff from the Maryland Zoo in Baltimore, Busch Gardens Tampa, and Adventure Aquarium in New Jersey. The three institutions have encountered similar cases in their penguin populations and explored a range of treatment strategies, with varying outcomes.

Krol and Dunker also consulted with Dr. Kim Tong, DVM, DACVS, a San Francisco-based veterinary surgeon who has performed surgical procedures at other zoo facilities throughout the Bay Area. They made use of the Academy’s ornithology collections to help inform their surgical approach, using a cadaver leg from a previous African penguin colony member as a model to determine the right position for the screw and washer, and also as a model for the technique illustration in the paper.

Tong led the carefully executed procedure along with assistance from Krol and Dunker, which consisted of carefully splitting the tendon longitudinally, inserting a screw through Iggie’s afflicted tendon and into the bone, and then sandwiching the washer on top. This kept the tendon in proper alignment and prevented further slipping. This method is based on the technique used in humans to stabilize ruptured Achilles tendons.

Following surgery, Iggie underwent extensive rehabilitation with the Academy’s highly skilled animal husbandry team. He was kept in a dedicated rehabilitation habitat off-exhibit for six months, returning to “fish school” to relearn how to swim and taking part in extensive physical therapy led by Academy biologists—all of which proved to be crucial to the procedure’s overall success. Today, Iggie has regained full mobility and is happily reintegrated into the Academy’s African penguin colony, where he is now indistinguishable in appearance and gait from his peers.

Sharing Knowledge and Offering Hope for Penguins with Perosis

A team of seven animal care professionals from multiple organizations—led by Krol as first author—collaborated on a scientific paper detailing four separate cases of perosis in penguins and their respective outcomes, including Iggie’s story. Co-authors included Dr. Freeland Dunker, recently retired longtime Academy veterinarian; Dr. Kim Tong, DVM, DACVS; and veterinary experts from the Maryland Zoo in Baltimore, Busch Gardens Tampa, and Adventure Aquarium in New Jersey. The full paper, now published in the Journal of Zoo and Wildlife Medicine, aims to provide veterinary professionals with comprehensive guidance for diagnosing and treating tendon-related issues in penguin chicks and other susceptible bird species.

“The successful treatment of little Iggie was only made possible through deep collaboration. At the Academy, we’re uniquely qualified to treat conditions like this since we have both veterinary expertise as well as industry-leading animal care. But equally essential to our process was the working group of peer organizations and talented advisors like Dr. Tong and our colleagues at AZA,” said Krol. “We’re proud to share Iggie’s successful case through this journal article in hopes that it offers other institutions a new tool for treating this challenging condition. It’s an important milestone, and underscores the power of working together to improve the lives of animals in human care.”

The Plight of African Penguins

The African penguin, which was recently uplisted by the IUCN (International Union of Conservation of Nature) to critically endangered status, faces declining populations in the wild due to reduced prey availability caused by a combination of climate change and commercial purse-seine fisheries, and habitat degradation. Since the 1800’s the species has seen a 99% population decrease, and continues on a downward spiral that could spell the birds’ extinction by 2030.

“Successful medical interventions, like Iggie’s, play a critical role in helping fight the decline and possible extinction of the African penguin,” said Brenda Melton, the Academy’s Director of Animal Care and Wellbeing. “In this particular situation, literally every bird counts, so the success of each procedure is worth its weight in gold.”

Visual Assets and Additional Information:

• Photos and video:
  • Social media video explaining Iggie’s condition and treatment (2 minutes)
  • Photos and video of Iggie getting a checkup, trying on the boot, swimming after surgery all available for use
  • Photos of the Academy’s African penguin colony on exhibit
• Penguin webcam:
  • To see Iggie in action, visit the Academy’s 24-hour penguin cam, and look for the feisty, adorable penguin with a white armband containing a black stripe on his right wing.
• Phenomena blog about Dr. Freeland Dunker
• Journal paper available for press upon request