Phoenix Zoo Orangutan Undergoes Surgery for Sinus Infection — See the Photos

The following images of Daniel the Bornean orangutan undergoing surgery may be disturbing to some viewers. 

Daniel the orangutan arrived at the Phoenix Zoo in 2013. He is one of four Bornean orangutans at the zoo. Previously, he lived at the Cleveland Metroparks Zoo and easily made the transition to his new habitat.

Daniel spends his days swinging on ropes, climbing on structures, frolicking in the grass and interacting with guests at the zoo through the glass.

Daniel has always struggled with his respiratory health, zookeepers said. To treat the condition, veterinarians administer a nasal spray in Daniel's nose, which is more effective than an allergy pill.

While veterinarians have worked to treat the symptoms of Daniel's respiratory conditions in the past, they knew it was time to try a long-term solution through surgery when his nasal infections infections kept returning.

Daniel is under general anesthesia as veterinarians prepare to operate.

Because the surgery has never been conducted on an orangutan in the U.S. before, a special team consisting of veterinarians and ENT specialists for humans were brought together to come up with a plan of action. 

"I thought I was getting pranked," ENT specialist Dr. David Simms said. 

"We are fortunate that we found an incredibly talented team willing to take on this complicated surgical procedure," said Dr. Gary West of the Phoenix Zoo. 

This is the first time a sinus operation has been performed on an orangutan in the United States. The surgery has only been performed a handful of times, most notably in the U.K. and Switzerland, around the world.

Respiratory illnesses and especially sinus infections are common in orangutans, the zoo said. 

While Dr. David Simms has performed the procedure on thousands of humans, he has never operated on an ape. In addition to reviewing CT scans, he familiarized himself with Daniel's skull by creating a life-sized model using a 3D printer.

The goal of the operation was to reduce the build-up of pus in his respiratory system, according to Dr. Jeff Steurer.

Veterinarians said had they not operated, his respiratory disease would have worsened and posed a risk to his life.

Bornean orangutans are considered a critically endangered species, with their habitat threatened by deforestation.

In order to permanently address his respiratory problems, surgeons created a permanent opening in his sinuses that would prevent new infections.

"We performed a marsupialization of the air sac, creating a permanent opening to help prevent reinfection," said Dr. Jeff Steurer.

"It may look a little odd and unsettling, but the end result will allow for continued drainage, thus preventing the buildup of the purulent material and the respiratory signs that are associated with it," Dr. Steurer said. 

Mary Yoder, the zoo's manager of primates, confirmed Daniel is back to his normal self following the surgery.

"He is doing fantastic," Yoder said. "He is active, his appetite has returned, he is engaging with guests and enjoys training with the animal keepers. He is back to his playful self."

Veterinarians and zookeepers say Daniel's surgery will prevent any other respiratory issues from arising in the future, helping him live a healthy and long life. 

Shortly after his surgery, zookeepers snapped a photo of Daniel enjoying the grassy fields in his enclosure.