The Great Ape Heart Project (GAHP) collects, reviews and archives echocardiograms (ultrasound exams) in an international database for gorillas, bonobos, orangutans and chimpanzees. We accept cardiac exams done on anesthetized and non-anesthetized apes so long as both a Submission Form and a copy of the echocardiogram are submitted. Please include still images that show all measurements performed, as well as at least one video image of each standard view obtained. Images should be submitted in DICOM format which allows review and confirmation of measurements.
Please email for a copy of our 2019 Boyd et al. JZWM guideline to echocardiography in great apes paper.

While we are currently continuing to accept exam submissions with alpha-2 agonists, our cardiac advisory team will not be able to provide an official report in these cases. Exam measurements obtained under alpha 2-agonists do not provide a truly diagnostic evaluation and may result in inaccurate diagnoses. Please review our Anesthesia page for more information on why we do not recommend using alpha-2 agonists for cardiac examinations. Exams are reviewed by our cardiac advisors and feedback is returned to submitting institutions within 6 weeks. Urgent clinical cases can be expedited for review upon request.

For more information about who should submit exams and how often they should be submitted, go to our Submitting Exams page.


Who should perform a great ape echocardiogram?

Obtaining the images needed for a diagnostic echocardiogram requires someone who is proficient in ultrasound imaging, ideally a specialist in cardiac imaging. Many zoos have local volunteer sonographers and cardiologists that come to the zoo during routine health checks, and who can assist in training for exams performed on awake animals.

If your institution does not have access to a sonographer or to an ultrasound machine, the GAHP has two volunteer sonographers on the project that are willing and able to fly out to zoos in order to assist with exams if the zoos can cover their travel costs. In May 2016, the GAHP purchased two Philips CX50 portable ultrasound units. One is designated for the 2015 IMLS Bonobo project and is kept on site at the Milwaukee County Zoo for use at bonobo-holding institutions. The other machine, which is available for loan for gorillas, orangutans and chimpanzees, is located at the Detroit Zoological Society. Please contact us at if you are interested in having one of our sonographers come to your institution.

Do I need to have a local cardiologist review the exam before submitting it to the GAHP?

No, you do not need to have your exam evaluated by a local cardiologist before submitting it to the GAHP. If you received a report from your local cardiologist, please include it with your submission.

What is the difference between a cardiac exam done on an anesthetized versus a non-anesthetized great ape?

An echocardiogram performed while an ape is sedated, or under anesthesia, is considered an “anesthetized exam”. Most great ape echocardiograms are performed while the ape is anesthetized for routine health monitoring or opportunistically when an ape is anesthetized for another health event. One of the advantages of an examination done on an anesthetized animal is that most sonographers are able to obtain all the necessary views and measurements for a complete cardiac evaluation based on the American Society of Echocardiography standards (ASE). Exams done on anesthetized apes also allow us to obtain additional clinical information that may be relevant to a cardiac health assessment.

Examinations done on apes without the use of anesthetics are often referred to as “awake” exams. In these cases, the ape is trained to present his or her chest to the mesh of the enclosure so that images of the heart can be obtained on ultrasound. A disadvantage to performing echocardiograms on non-anesthetized apes is that it may not be possible to obtain all the views and measurements needed for a full cardiac assessment, especially in one training session. It is most common for an exam submission done on awake apes to span several training sessions within a 30-day period, with trainers and sonographers working to complete all the views over multiple days. This is one of the reasons that the GAHP does not recommend using echocardiograms done without the benefit of anesthesia to replace cardiac exams done when sedation is feasible. Another disadvantage to non-anesthetized exams is the potential to miss other health problems. However, there are still many advantages to performing echocardiograms on non-anesthetized apes, for example:

  • When sedation is not feasible or infrequent – In older apes or apes with known cardiac disease, the risks of anesthesia may be unacceptably high. Also, some zoos do not perform routine anesthetized health checks as frequently as other zoos do. In these cases, being able to perform a cardiac exam in an awake animal may provide information that would otherwise be unavailable.
  • When apes with known heart disease are on cardiac medications – When an ape receives cardiac medications, the ultimate hope is that the drugs will either slow down the progression of the disease, or better yet, it will improve heart health over time. Routine cardiac monitoring such as serial and frequent echocardiograms may provide clinicians with an indication of clinical response to medications and allow for alterations in medications if no improvements are seen.

Why should I train for “awake” ultrasounds?

While echocardiograms done on non-anesthetized apes are particularly useful for apes that cannot be anesthetized or for apes that are being monitored for known cardiovascular disease, it is still useful to train for and obtain “awake” cardiac ultrasounds from your apes whenever feasible. Consider the situation where an ape in your collection becomes ill and it is determined that he or she has heart disease. That ape may be less willing or motivated to participate in a new health training activity than when they were healthy and feeling well. An ape that is already trained for awake cardiac exams may be more willing to participate at a time where it becomes critical to routinely monitor him or her.

How do I obtain ideal cardiac images?

The GAHP has published a guide to echocardiography in great apes in the Journal of Zoo and Wildlife Medicine (Boyd et al. 2019 JZWM). If you do not have access to JZWM articles, please email for an author’s copy. We also recommend reviewing the American Society of Echocardiography’s guidelines and the British Society of Echocardiography’s paper on ideal ultrasound cardiac imaging. For training and body positioning advice for obtaining images, our GAHP ultrasound advisors, Leann Beehler and Bobbie Boyd, are available to answer questions by phone or email. Please send a message to to get in contact with them.

How does anesthesia affect cardiac measurements and exam interpretation?

Drugs that are frequently used for immobilization of the great apes include ketamine, with or without adjunct tranquilizer (such as midazolam or other benzodiazepine); Telazol™, a proprietary mixture of tiletamine and zolazepam (also referred to Zoletil in other countries); and medetomidine, in combination with either Telazol™ or ketamine. All of drugs / drug combinations generally provide safe and effective immobilizations, however alpha-2 agonists (e.g. medetomidine) may present a significant risk to apes that are predisposed to or already have cardiovascular disease.

If you plan on performing a cardiac assessment under anesthesia and would like to submit the exam to the GAHP for review and inclusion in the database, we ask that you consider not using alpha-2 agonists such as medetomidine. Exam measurements obtained under alpha 2-agonists will not provide a truly diagnostic evaluation and may result in inaccurate diagnoses. While we are currently continuing to accept exam submissions with alpha-2 agonists, our cardiac advisory team may not be able to provide an official report in these cases.

Our GAHP anesthesia advisor, Dr. Ben Brainard, has created a review of anesthetic effects on cardiac ultrasound evaluations with additional references to consider (download pdf). If you have any questions about anesthesia considerations for a cardiac exam, please contact us at

Why does the GAHP Exam Submission form request body measurements?

At minimum, the GAHP requests that you measure crown-to-rump length when completing an anesthetized cardiac exam (line 1 on the form). Height and weight measurements are an important part of the overall cardiac assessment.


The normal, or healthy, cardiac reference range for great ape is just that – a range. Unlike when a human visits the cardiologist, the GAHP cardiac advisory team usually does not get to meet the patient they are evaluating. That is why it is important to have height and weight information included in the submission form so the cardiologist has an idea of the ape’s overall size. For example, a gorilla’s left ventricular measurements may be on the higher end of the reference range for his age and sex, which may or may not be an indication that he is developing heart disease. However, if that gorilla is very tall, higher values may not be as alarming than if he were a smaller gorilla. Submitting height and weight measurements is also useful to determine whether an ape is overweight, as obesity is believed to play a role in the development of cardiac disease.