Under (Blood) Pressure: Monitoring Heart Rates in Zoo Primates

How do you get an orangutan to sit still for an electrocardiogram? All it takes is a little patience and a lot of ingenuity! The Smithsonian’s National Zoo’s positive reinforcement training program enables primates to voluntarily participate in their own medical care without the need for anesthesia.

How do you get an orangutan to sit still for an electrocardiogram? All it takes is a little patience and a lot of ingenuity! The Smithsonian’s National Zoo’s positive reinforcement training program enables primates to voluntarily participate in their own medical care without the need for anesthesia.

Learn all about their efforts to monitor orangutan, gorilla and Allen’s swamp monkey heart health from primate keeper Erin Stromberg and veterinarian Katharine Hope.

Why is it important to know an animal’s heart rate?

Hope: Just as with humans, cardiac disease and diabetes can be present in non-human primates. Monitoring cardiac parameters and blood glucose in our animals is paramount to maintaining their health.

Stromberg: As an animal keeper, my primary goal is to provide the best welfare to the primates in our care. This entails being on the lookout for the latest techniques and best practices for assessing their health in the most accurate, timely and least stressful way possible.

Recently, we trained our gorillas and orangutans to use a new device that records their heart rate and electrocardiogram (ECG) information, allowing keepers and veterinarians to track their normal heart patterns and rates without the need for anesthesia.

At the same time, our male Allen’s swamp monkey Nub Armstrong has been an extremely cooperative patient, allowing us to take blood glucose and blood pressure readings from his tail voluntarily. Because anesthesia can impact these levels and push them out of their normal range, this training allows us to get more accurate values and improve our interpretation of Nub’s health status.

How do you take these readings?

Stromberg: At the Zoo, we are big advocates of positive reinforcement training, which gives our animals the option to choose to participate in their own care. These interactive training sessions also help build trusting relationships between the animals and us. They know that if they do the behavior asked of them correctly, they will receive a reward — usually a combination of food and an emphatic “good job” from their keeper.

To take the orangutans’ and gorillas’ ECG measurements, I hook my phone up to a pad with built-in electrodes. To get a proper reading, the apes must reach their fingers through the mesh, place them on the electrodes and hold them there for 30 seconds. While they sit still, I reward them with dilute juice from a squeeze bottle. They don’t seem to mind the phone at all. Between keepers and visitors, they are very familiar with them!

Nub Armstrong’s process is a bit different. To get his blood pressure reading, I will put a cuff around the base of his tail and inflate it. Then, when it comes time from the glucose reading, we prick the skin of his tail to get a drop of blood. He is one of the most stoic and patient monkeys I’ve ever worked with, which makes him an ideal candidate for this training. No matter the situation, if there are peanuts in play, he is dedicated and focused on the task at hand.

What is the key to training great apes and monkeys?

Stromberg: Each animal learns differently, and it is the keeper’s responsibility to understand what each animal needs in order to successfully train a behavior. It is key that we treat our animals as individuals and allow them to go at their own pace. With the orangutans and gorillas, some picked up the behavior very quickly, mimicking where I put my hands on the reader. Others needed a bit more time to figure out exactly where to place their fingers and for how long to hold still.

Hope: Voluntary participation makes the process for administering medications and diagnostic exams run smoother, too. Although some medications come in pill form and can be hidden inside tasty treats, others — like vaccines — are administered by hand through training sessions. Also, in order for us to complete radiographs, ultrasounds and laser therapy, animals must voluntarily “station,” or hold still, for these treatments so that they can be performed safely. The animals are usually willing to participate, even when it involves momentary discomfort from a needle stick, if they know they will receive a reward afterward.

Are there any challenges in training this behavior?

Stromberg: Making sure that the primates don’t break any of the medical equipment! Although they are very eager to train, they are also curious about new things. Naturally, the best way to investigate the device is to take it from the keeper and pull it into their enclosure for further inspection. To prevent this, we do our best to structure these training sessions so that the interactions with us and the food rewards they receive are more enticing than the equipment.

The only difficulty I am having is getting an ECG reading from our silverback gorilla, Baraka. He’s got massive, thick fingers and long fingernails, which make it difficult for there to be enough finger pad-to-electrode contact to get a full reading. I think I need to train Baraka to accept a manicure from the keepers so that his ECG will be quicker and easier to obtain.

Do any of the gorillas or orangutans not participate?

Stromberg: Our little guys. Western lowland gorilla infant Moke, who is 1.5 years old, and Bornean orangutan infant Redd, who just turned 3 years old, don’t participate in the ECG readings yet. It’s not because they cannot be trained to do it, but because these youngsters won’t sit still for three seconds, let alone 30 seconds!

What is most rewarding about training these behaviors?

Stromberg: I feel a great sense of accomplishment whenever I am able to get a successful reading from an animal while they are awake. I take great pride that training for each of these medical measurements — be it blood glucose, blood pressure or ECG and heart rate — is helping to improve the overall health and welfare of our animals and could potentially decrease the need for an exam under anesthesia.

Positive reinforcement training has allowed for amazing advancements in the medical care of animals at the Zoo. It really takes a village, with cooperation from the animal care team, the veterinary team and, of course, the primates.

I greatly appreciate the active role and progressive thinking of our veterinary team. They work side by side with us to train medical behaviors and help us ask (and answer) the question: What can we do to provide our animals with exceptional health care? Without their willingness to allow keepers to try new techniques and equipment to get these measurements, it would not be possible to train these behaviors.

This story appears in the November 2019 issue of National Zoo News. Daily keeper talks take place at 11:30 a.m. at Think Tank and 1 p.m. at the Great Ape House. Don’t miss a special research presentation at Think Tank at 1:30 p.m. on Tuesdays through the beginning of December.