Report on Heat-Related Primate Death Sent to Regulators

The University of California, Davis, is submitting an external reviewer’s report to federal regulators following the heat-related death of a rhesus macaque after being transported in a university van.

We deeply regret the preventable death of this animal. As home to one of the largest animal care research programs in the country, the welfare of every animal at UC Davis is our highest priority, and the avoidable death of any animal in our program is a tragedy. We are taking immediate actions to prevent an event like this from occurring again.

At the recommendation of the vice chancellor for Research and the associate vice chancellor for Research and Teaching Animal Care Program, UC Davis commissioned Christian Abee, professor emeritus at the University of Texas, to conduct an independent review immediately following the incident and is implementing the recommendations of his report.

On the morning of May 12, 2023, two adult rhesus macaques were transported from the California National Primate Research Center to another facility. The approximately 15-minute trip used one of the center’s vans, which have been in use for some years without incident.

At the destination, following previous practice, one animal was taken inside while the other remained in standard caging within the van. Staff were delayed in returning to the van and when they did, they found the animal comatose. They began cooling and resuscitation procedures and the animal was brought back to the intensive care unit at the California National Primate Research Center, where veterinarians made the humane decision to euthanize it. Necropsy findings were suggestive of heat-induced injury.

Immediately after the May 12 incident, UC Davis verbally notified federal agencies regulating animal research (the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service and National Institutes of Health Office of Laboratory Animal Welfare) as well as AAALAC, an international body that accredits animal research facilities. Professor Abee was commissioned to review the incident and make recommendations.

In addition, the center took the following immediate actions:

  • Ten-day pause in all transport of nonhuman primates off site.
  • Transport van taken out of service until June 23 for inspection of HVAC system.
  • Practice changed so only one animal transported at a time and no animal left unattended in vehicle.
  • Initiated purchase of a new van with thermostatically controlled heat and air.

During the course of the review, an animal was found to have an elevated temperature after being transported to the same facility. During this transport, there were no other animals in the van, and the air conditioning was running. The animal did not show other signs of heat stress and was later returned to the California National Primate Research Center without further incident. The reviewer relied on this incident to make additional recommendations for improved procedures.

Abee’s review included a site visit, interviews with staff and review of documents and procedures. Among his findings, Abee determined that in the May 12 incident, an overhead heater in the back of the van was switched on, causing the vehicle to overheat. The incident could have been avoided if the van had been equipped with a thermostatically controlled heater, and/or if the animal had not been left unattended for a substantial time, he wrote. Abee noted that the factors leading to this adverse event were not anticipated within the standard operating procedures, nor from prior experience transporting animals.

The review’s recommendations call for all animal transport, holding and housing facilities to have thermostatically controlled heating and cooling that can maintain a steady temperature. Abee recommended review and updating of standard operating procedures to ensure regular, frequent checks on animals, that no animal should be left unattended, and to take into account the age and clinical condition of animals being transported. He also recommended additional staff training.

UC Davis has accepted the review’s findings and is implementing all of the recommendations.

In addition, the center is establishing a new, permanent committee for enhanced, ongoing, continuous review of all standard operating procedures related to animal welfare and safety.

“At UC Davis our goal is continuous improvement of animal care so that our programs meet the highest standards. We will take whatever actions are necessary and appropriate to achieve this objective,” said Jeffery Gibeling, interim vice chancellor for Research.

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Copy of report 

Media Contact:

  • Andy Fell, News and Media Relations, 530-304-8888,

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