Off the Cuff: An Inside Look at Voluntary Blood Pressure Readings with our Great Apes

Posted July 1, 2021 by Theresa Clyatt-Larson

By: Theresa Clyatt-Larson, Victoria McGee, and David Orban

When you visit the doctor, you typically get a blood pressure reading. It’s a simple process that we don’t think too much of – the nurse wraps a fabric or plastic cuff around your arm, and then either turns the machine on or manually inflates the cuff. You may feel slight discomfort as the sleeve tightens, but it’s a painless process that gives your doctors insight into your cardiovascular health.

But how exactly would you go about getting a blood pressure reading on an orangutan, bonobo, or gorilla? As wild animals, and due to their strength and unpredictability, zoo staff never share the same space with them. So, we have to obtain this information using protected contact and voluntary participation from these great apes. Blood pressure data provide a foundation for successful veterinary care, and troubleshooting the logistics of getting accurate data is well worth the effort, considering our goal is to provide the best healthcare possible to the great apes in our charge. And that’s where collaboration and innovation come into play!


  Since we cannot enter the same spaces as great apes, we need a durable device that an orangutan, gorilla, or bonobo will willingly put their arm into. This is where the tough cuff – a hard dense plastic cube with the center cut out – comes in.  Keepers then attach the fabric or plastic cuff (that would be wrapped around human arms) inside the tough cuff. This then inflates and takes a blood pressure reading! However, the original tough cuff was designed for male gorillas. Due to the large arm size of a male gorilla, the tough cuff does not work on its own for female gorillas, orangutans, or bonobos.

In order to customize the size of blood pressure cuff holder to the great ape individual (and thus ensure the accuracy of the blood pressure reading), we turned to some student partners at the University of Cincinnati (they’ve each graduated as of now). Jack Buehler, Ben Merk, & Andie Ticknor had previously worked with the Zoo on an enrichment project for giraffe, so they were the perfect partners to work with again. The three students visited the Zoo and met with some our primate keepers to fully understand the challenge and take some measurements of what’s needed. They then drew up some 3D print schematics and took their order to the 1819 Innovation Hub at the University of Cincinnati for printing!

The end result was 4 different sized inserts for the blood pressure cuff, each one facilitating an accurate blood pressure reading.  With these new inserts the keepers have been able to get a better fit of the fabric cuff around each of the great apes’ arms, which has allowed for accurate blood pressure readings.


But just because we have the proper materials does not mean that we automatically get blood pressure readings! We also have to work with our great apes to voluntarily position and hold their arm within the tough cuff.  This requires a trusting relationship between animal care professionals and each great ape participating in the behavior. We build these relationships through positive reinforcement training. In this training style, behaviors we look for are partnered with a cue – which allows us to “ask” for the behavior – and then reinforced once given.

When it comes to a complex behavior like a voluntary blood pressure reading, the behavior is broken down into smaller steps. These approximations allow the individual to learn the behavior in an achievable way. For example, two of our Jungle Trails keepers (Theresa & Jon) are shown working with Henry the Sumatran Orangutan. In order to get the final behavior, they had to get Henry comfortable with extending his arm into the mesh rectangle that extends from one of his holding spaces. Theresa and Jon then introduced the tough cuff; once he acclimated to that new item, they began the process of desensitizing Henry to the inflating of the blood pressure cuff. While this requires Henry to sit through a potential apprehensive process at first, he is reinforced with pineapple for calmly sitting through the procedure. Henry chooses to participate in the medical data collection because of his trusting relationship with his keeper team, in addition to being reinforced with fruit and positive attention for his time.


With the proper equipment and dedicated training, Henry has the opportunity to actively participate in his own healthcare. This provides veterinary staff with the most accurate data to monitor his heart health. Regular blood pressure readings, obtained when Henry is calm and in good health, provides a baseline. Because we understand his “normal,” we’ll be able to assess any changes in heart health as he ages.

     Since cardiac diseases are the number one health issue in older great apes in human care, it’s crucial to proactively monitor heart health. Early intervention strategies, when needed, can extend the life of great apes and allow them to have a better quality of life. Understanding Henry’s heart health allows us to do just that if it is ever needed! And this data contributes to a better understanding of blood pressure values among other orangutans in managed care settings.

Thanks to the hard work of the students at the University of Cincinnati and animal care professionals, we can have the best understanding of Henry’s cardiac health and contribute to data collection for his species. The collaboration allows Cincinnati Zoo & Botanical Garden to provide the highest standards of care to its great ape residents, supporting Henry, the gorillas, and the bonobos so they can live the best life possible in our care!