"Good. Hold," said great ape keeper Amanda Bania to the 200-pound gorilla Kojo as she held what looked like a computer mouse to his back.
The western lowland gorilla leaned his back against his cage at the National Zoo in Washington while being hand fed grapes by zookeeper Elliot Rosenthal.
“Kojo is pretty happy to hold as long as he’s getting grapes,“ said Bania. She then downloaded heart data from an Implantable Loop Recorder (ILR) that had been surgically placed between Kojo's shoulder blades to track his heart rates and rhythms.
While Kojo was chowing on fruit, he was also providing valuable data to help scientists solve a scientific mystery: why do gorillas have problems with their hearts?
Heart disease is a major cause of death among great apes in human care according to Dr. Hayley Murphy of the Great Ape Heart Project. They estimate that cardiovascular disease plays a significant role in the mortality of over 40% of captive gorillas.
Both Kojo and Kwame - a fellow western lowland gorilla - are part of a project to gather clinical data aimed at improving treatment and preventing heart disease among great apes.
“As we monitor what’s normal for both Kojo and Kwame, we are then going to be able to pick up on minute changes that will help us identify heart disease before they develop clinical signs. That means we can treat them earlier and we can keep them alive longer,” said Suzan Murray, the zoo's chief veterinary medical officer.
This is the first time the ILRs have been used in gorillas, although the technology has been available for human use for many years.
In humans, the ILR is placed in the chest area where it can easily pick up heart rhythms. But that location does not work for the gorillas - who can easily reach their chest area and may try to pull out stitches from the surgery.
"We found a place in the back where we can implant the ILR and it doesn't bother the gorilla," said Murray.
Then, they had the animal keepers work with Kojo and Kwame to teach them to present their backs and hold for about 30 seconds so the data could be gathered.
The research marks a critical first step, said Murphy, because experts can now track gorilla cardiac function without using general anesthesia. Gathering data this way both lowers the risk to the animals and keeps the data from being altered by the use of drugs.
Animals in the wild tend to hide signs of sickness as a protective measure until the last minute.
"That's been an issue with cardiac disease and gorillas," said Murray. "Before we knew about this disease process, a lot of gorillas presented with sudden death. They were fine one minute and then found dead the next minute."
The ILR will give the doctors an early heads-up to gorilla heart problems.
"As our closest living relatives, it is critical to both human and ape health to figure out why the apes are dying of cardiac disease in zoos and how this disease pattern relates to or differs from human heart disease," said Murphy. "If we can determine what is causing ape heart disease, and how to effectively prevent and/or treat the disease, we may provide clues to improving human cardiac health."