As a hand surgeon, Peter Jebson, MD, doesn’t usually make house calls.
But when his patient is a 180-pound chimpanzee, he makes an exception.
His patient, a 32-year-old chimpanzee named Susie, had a mysterious lump on the back of her right wrist.
The keepers who care for the zoo’s six chimpanzees noticed the swelling a couple of months earlier, said Ryan Colburn, DVM, the zoo’s veterinarian. The veterinary team monitored the swelling, using Susie’s training to get her to show her wrist for examination. But a full diagnosis required a more comprehensive exam.
When Dr. Colburn examined the round, 1-inch lump, many possible explanations occurred to him—from a harmless cyst to a malignant tumor.
He decided to consult a specialist.
As the zoo’s vet, Dr. Colburn provides health care to more than 2,000 animals, encompassing 210 species. He treats everything from colds to cancer in creatures great and small, from nose to tail and from beak to claw.
And at times, he calls in other veterinarians, as well as dentists and physicians who treat human patients.
“When you’re practicing zoo medicine, you are the ultimate generalist,” he said. “Our expertise comes in caring for so many different species. Partnering with specialists can give us their focal knowledge when we need it. By working together, we can provide the best care possible for all our patients.”
For Susie, it made sense to consult a surgeon with expertise in treating human hands.
“For chimpanzees, one of their closest relatives is the human being,” he said.
Dr. Colburn and zoo staff members did an online search for local orthopedic doctors and started contacting their offices.
When he got the call, Dr. Jebson readily agreed to help out. He and his wife love animals. They have traveled to Africa, New Zealand, Australia, the Cook Islands and the Galapagos Islands to see creatures in their natural habitats.
And he brought considerable expertise to the case—in his 23 years as a hand surgeon, he has examined thousands of hands. All human, however. This case was a first.
Anesthetizing a chimpanzee
At John Ball Zoo, the keepers took special precautions to prepare Susie for the exam.
With their long arms and powerful hands, chimpanzees possess much greater strength than humans. Although Susie is usually a calm, easygoing creature, she could become dangerous if alarmed.
A couple of weeks in advance, the keepers had her practice raising her arms and sitting still for a pre-surgery shot, said Bill Flanagan, the curator for the chimpanzee exhibit. The workers kept a mesh screen between them and Susie for safety.
They tweaked her routine every day, so she wouldn’t become suspicious and uncooperative on exam day.
“(Chimpanzees) are so smart,” Flanagan said. “Even when their routine is a little bit off, they know something’s up.”
The preparations worked beautifully. On a sunny September morning, Susie sat calmly to receive the injection in her arm to put her to sleep. As she slept soundly, Dr. Colburn and another zoo team member put her on a stretcher and transported her down the hall to the exam room.
They intubated Susie and inserted an intravenous line in her arm, so they could administer medication and fluids during the procedure.
Dr. Jebson examined the lump on Susie’s wrist. He aspirated fluid from the mass and looked at X-rays and ultrasound scans.
He believes the mass is a benign tumor. It is most likely a lipoma—made of soft tissue, or a fibroma—made of fibrous or connective tissue.
He saw no need to remove or treat the mass that day. The zookeepers said it didn’t seem to bother Susie: She didn’t pick at the bump or favor her right hand.
“At this stage, our decision is just to observe it for now,” he said.
If it grows or changes, he may someday remove the lump and perform a biopsy.
Dr. Jebson also examined a second area of concern—a swelling on the back of Susie’s knuckles. He determined it was a post-traumatic hematoma—a bruise caused by striking something.
Chimps hit objects with the back of their hands as a form of communication, so the finding did not surprise the zookeepers.
Throughout the procedure, a zookeeper held Susie’s left hand. In addition to a variety of anesthetic monitors, this is one of the ways to monitor the depth of the anesthesia, Dr. Colburn said. If Susie’s grip tightened, it could be an early sign that she could wake up.
“We need her to be as safe as possible, but we also can’t have her waking up on us,” he said. “We have to balance those two things.”
For Dr. Jebson, the experience offered an eye-opening window into human-chimp connections.
“It’s fascinating,” he said. “You’re looking at relatively the same anatomy.”
Compared to humans, Susie had an exceptionally long palm, a short thumb and long, slender fingers.
But the same creases stretched across her leathery palm. She had the same arrangement of finger bones and knuckles. Similar connecting tendons gave her the ability to grasp and release.
“Our norm is the human wrist and human anatomy,” Dr. Jebson said. “Switching from that and taking what we know about human anatomy, morphology and patho-anatomy into a chimpanzee is amazing. It’s very cool.”
While Susie was under anesthesia, Dr. Colburn made use of the time to fully examine her. He performed an abdominal ultrasound, had her teeth cleaned and drew blood for routine blood work.
An echocardiogram of her heart was performed by Robert Sanders, DVM, a veterinary cardiologist from Michigan State University College of Veterinary Medicine.
As Susie recovered after the exam, Dr. Jebson went to the outside viewing area for the chimpanzee exhibit.
A 21-year-old female chimp, Kiambi, sat on a bridge, her arm stretched up to grasp a rope. She watched her visitors intently.
“She is the youngest and she tends to be very mischievous,” Flanagan said. “She also has a real high level of emotional intelligence. She keeps track of how the others are feeling. If one of them is not doing well, she looks out for them.”
As if scripted, a 41-year-old male chimp named Sam showed how chimpanzees use their hands.
He jumped up to the viewing window and banged on it with the back of both hands, in a dramatic show for attention. And he used a stick to draw a smoothie mixture from a feeding spot, impressing Dr. Jebson with the dexterity of his long fingers.
“Amazing,” he said. “Absolutely amazing.”
The diagnosis for Susie was the “best news for her,” Dr. Colburn said. He appreciated the insights Dr. Jebson brought to her care.
“He knows the human hand and diseases and processes and injuries that can happen,” he said. “We knew his expertise would help us narrow it down.”
Dr. Jebson hopes he and other Spectrum Health physicians can continue to serve as a resource for the zoo.
“I think it’s a great collaboration,” he said. “And it’s fascinating to me because of the anatomy in contrast to the human hand. It was a privilege to be able to examine a chimpanzee like that.”