If you look closely at the Phoenix Zoo's 11-year-old orangutan Daniel, you'll see what looks like an open wound on his chest.
But it's supposed to be there.
Daniel recently had surgery for a bad sinus infection that spread to the air sac -- the pouch on the animal's throat. Letting it go much longer could've resulted in pneumonia or even death.
"He had airsacculitis, an infection in that sac system and sinusitis. So we really wanted to address both of those at the same time," said Dr. Gary West, Executive VP of Animal Health and Living Collections at the Phoenix Zoo.
But orangutan sinus surgery? It's not an everyday procedure. Who would do it?
"I thought it was a joke or a prank at first," laughed Dr. David Simms, a Valley ENT physician.
Yes, Simms is a doctor who typically only sees human patients. But he agreed to the procedure.
He studied a 3-D copy of the ape's skull, made from the animal's CT scan. Simms had performed surgery hundreds of times, but never on an animal.
"It was pretty strange operating on an orangutan," said Simms. "There was a big difference in appearance from a human."
Dr. Jeff Steuer, a veterinarian surgeon, worked with Simms on the surgery.
"It's not something you get to do every day," he said. "I spend most of my days working on dogs and cats."
But the two got the procedure done.
The surgery is believed to be the first of its kind in the U.S. Dr. Simms said it's been performed in Europe, but there was no follow up information available to know if it was successful.
So far, Daniel's handlers said, he seems to be doing better.