Why monitor blood pressure in great apes?

Taking blood pressure readings is a common practice for measurement of blood pressure. Persistent high blood pressure is called hypertension. The presence of high blood pressure means that the heart needs to work harder in order to pump blood through the bloodstream to the body’s vital organs to sustain oxygen delivery, and this can lead to heart damage over time.

In humans, the normal range for blood pressure values has been defined. According to the American Heart Association, healthy or “normal” blood pressure in a human is anything less than 120/80 mm Hg. High blood pressure readings, specifically over 140/80 mm Hg, may indicate underlying heart disease or other systemic disease (e.g. kidney disease). Reference ranges for blood pressure in great apes have not been established and therefore we cannot accurately say whether apes suffer from hypertension or not until these parameters can be taken under controlled circumstances, recorded systematically, and assessed for patterns.

If we serially monitor blood pressure in an ape under normal conditions, we would expect to gain a sense of what is “normal” or “base-line” for that individual ape. If blood pressure values later become elevated and remain elevated over time, this is an indication to perform an echocardiogram as well as a systemic evaluation (e.g. serum chemistry, abdominal radiographs) to determine what is causing the hypertension.

Another reason to monitor blood pressure in apes is to monitor the adequacy of dosing of antihypertensive medications. An ape with suspected hypertension will be given drugs that lower blood pressure. The best way to know if the dose is working correctly is to monitor blood pressure serially and to make sure that the blood pressure values go down over time. It is useful to continue monitoring a medicated ape’s blood pressure because blood pressure may go up again for various reasons, and changes to the dose may be required periodically.

Blood pressure monitoring in apes can be time consuming, as it requires initial training for the procedure, followed by long-term routine monitoring. If training time is limited, keepers and veterinary staff should work together to prioritize training goals depending on which apes may be at high-risk for heart disease or are already diagnosed with CVD.

How can I monitor blood pressure in great apes?

There are several non-invasive ways of obtaining blood pressure measurements. Blood pressure in humans is most commonly obtained by using an automatic, cuff-style, bicep (upper-arm) monitor. It is also possible to obtain blood pressure invasively by using a specific catheter inserted into an artery. This method is considered the “gold-standard” for obtaining blood pressure as it is believed to provide the most accurate reading. During an exam on an anesthetized ape, blood pressure monitoring can be accomplished by either method or sometimes both methods.

In order to measure blood pressure serially over time, without the risks of repeated anesthesia and without the effects of systemic anesthetics, it is usually necessary to train apes to have their blood pressure monitored without anesthesia. For these non-anesthetized, “awake” apes, the best way of monitoring blood pressure at your institution is using the equipment and methods that are available and work best for you. Here are some commonly used blood pressure monitoring devices for apes:

Adult Male Gorillas – the “Tough Cuff” is a polycarbonate (plastic) device that is used to contain an inflatable blood pressure cuff within a cage-mesh sleeve. A cage-mesh sleeve is typically a removable extension of caging that allows an ape to safely present his or her arm to a keeper. The Tough Cuff and variations of the device have most commonly been used with zoo-living, adult male gorillas.

For smaller-armed apes (female gorillas, orangutans and chimpanzees), the Tough Cuff needs to be made smaller or an insert is needed in order to use the correct sized cuff.

For more information on how to obtain a Tough Cuff or to build similar device, please visit our BP Monitoring Devices page.

Bonobos – bonobos are the smallest of the great apes. Bonobos have more slender fingers than gorillas, orangutans and chimpanzees and so it has been possible to use a finger-cuff blood pressure device for monitoring blood pressure in bonobos. For more information about finger-cuffs, please visit our Bonobo Blood Pressure Project page.

Does the GAHP want me to submit blood pressure readings?

The GAHP Cardiac Exam Form (.docx) requests blood pressure readings that are obtained during anesthetized exams.

In early 2016, the GAHP began a two-year study investigating blood pressure in bonobos using a PetMap™ finger-cuff monitoring device. The GAHP is currently only accepting bonobo data for this study but encourages institutions to independently work on projects related to blood pressure monitoring.

Does the GAHP recommend any particular blood pressure monitoring device?

Please refer to our BP Monitoring Devices page for information about the types of devices used at various zoos. We do not have specific recommendations for blood pressure equipment.