The CNPRC houses about 4,500 monkeys, mostly rhesus macaques (Macaca mulatta). This species is widespread in Asia, especially in India where they are often found in urban areas, and in China. They can adapt to a wide range of climates. The vast majority of the monkeys at UC Davis are bred on site, with a few obtained from other facilities. No monkeys are obtained from wild populations.
Rhesus macaques live in extended family groups consisting of a few males and a number of females. Many of the monkeys at UC Davis live in half-acre outdoor corrals where they can form such family groups and complex social networks.
The rhesus macaques at the CNPRC can live to 30-38 years, far longer than their normal lifespan in the wild of up to 19 years. Many of the geriatric animals remain in the outdoor corrals with family members of all ages in the rich social environment of their home community. The aged rhesus colony at the Center provides distinctive opportunities to better understand normal aging changes and to develop new treatments and solutions for age-related health problems.
The center also houses a small colony of South American titi monkeys (Callicebus cupreus). There are no chimpanzees or other apes at the center.
Since most biomedical research on human diseases cannot be conducted on humans for ethical reasons, animals are essential for understanding disease processes and for testing the safety and efficacy of therapies.
When studying human diseases, monkeys provide one of the best animal models. Humans and monkeys bear a close genetic relationship, reflected in many anatomical, behavioral, developmental, physiological, and reproductive similarities.
For example, rhesus monkeys, unlike other mammalian species, have a menstrual cycle and hormonal patterns comparable to humans, which means they are necessary to study issues related to fertility, pregnancy, and changes that occur with menopause. Monkeys are also susceptible to an immunodeficiency virus similar to HIV, making them ideal for the study of AIDS and new vaccines and drug treatments. Since monkeys in breeding colonies can live well past their typical lifespan in the wild, they also provide opportunities for aging research, including studies on Alzheimer’s disease. Nonhuman primates have made significant contributions to the study of hepatitis, malaria, respiratory viral diseases, Parkinson’s disease, stem cell transplantation, and gene therapy.
Researchers also study the family structure and behavior of monkeys living in outdoor corrals to learn more about the behavior of these primates in the wild, and how this knowledge can be applied to understanding human behavior. Students and other trainees from across the campus, such as those in anthropology, veterinary medicine and animal science, are able to carry out research projects at the Center under the guidance and mentorship of Core Scientists.
The CNPRC is a national resource and provides opportunities for research to investigators around the U.S. The CNPRC has 18 core scientists, who hold joint appointments with various departments at UC Davis. The center also hosts around 70 affiliate scientists from UC Davis and other institutions, who work with core scientists on their research projects or conduct independent research. Many affiliate scientists are located in California, but others are located at institutions throughout the world.
Animal research occurs alongside other types of studies, including human clinical and epidemiological research, as well as alternatives to whole live animal research such as cell cultures and computer simulations. In fact, consideration of viable alternatives to research with live animals is a basic ethical principle that undergirds the conduct of all research with nonhuman animals. Furthermore, this principle is implemented through a stringent regulatory oversight system that mandates review and approval of such research, at multiple levels.
Nonhuman primates are studied when there are no feasible current alternatives to address the research question.
The CNPRC follows the principles of “reduce, refine, replace”, the 3Rs. Whenever possible, researchers must reduce the number of animals needed, refine how experiments are conducted, replace animals with others (e.g. mice instead of monkeys), or replace animal tests with cell cultures or computer models. It is currently not possible to completely replace animal models with computer simulations or cell cultures. The CNPRC also recognizes the importance or Rigor and Reproducibility, the two cornerstones of science advancement.
Imaging technologies are used to maximize the use of animals required and aid in ensuring rigor and reproducibility. For example, Primate Center scientists extensively utilize a range of imaging techniques provided in the Multimodal Imaging Core such as ultrasound, optical imaging, and Positron Emission Tomography/Computer Tomography (PET/CT). A human PET/CT scanner is regularly used for noninvasive imaging of animals to develop new techniques and imaging capabilities for use in humans. The Core has also incorporated the world’s first total-body PET scanner for a myriad of research studies which will revolutionize PET imaging in humans.
Rhesus monkeys, one of the most common species used in biomedical research, share about 93 percent of their genes with humans. They are also widely used because they breed well in captivity. Rhesus monkeys offer many advantages because of their close similarity to humans.
Nonhuman primates, including rhesus monkeys, are essential to understand biological functions, study complex human diseases, and address safety of new diagnostics and therapies proposed for human use. They share many important features with humans because of their close genetic relationship; similarities in reproduction, development, physiology, immunology, anatomy, genetics, cognition, and social complexity aid in overcoming the roadblocks to new human treatments. Monkeys and humans share many reproductive features including a similar menstrual cycle. Thus, there is an ongoing need for nonhuman primates that parallel the human condition, and within a supportive infrastructure with the necessary expertise to facilitate access and use.
The vast majority of the monkeys are bred on site. The Center occasionally acquires a small number of monkeys each year from other primate breeding facilities. No monkeys are obtained from wild populations.
About two-thirds of the Center’s approximately 4,000 monkeys live outdoors. Monkeys are provided the best of veterinary care and living conditions. They are housed either in half-acre field corrals or conical-shaped “corncribs.” Outdoor enclosures contain swings, jungle gyms and shelters for the monkeys, as well as supplemental heat during the winter months. Indoor monkeys are housed in cages and paired with another monkey for companionship during the day. The center’s exemplary Environmental Enrichment Program utilize appropriate social housing, toys, fresh fruits and vegetables, and other activities.
In the wild, a rhesus macaque’s life span is up to about 18 years of age. At the CNPRC, with excellent nutrition and medical care, these animals can live up to 38 years of age. Some geriatric animals are housed in the outdoor corrals with family members of all ages in the rich social environment of their home community. In addition to day-to-day health care for all animals, geriatric animals receive semi-annual veterinary evaluations (e.g., physical examination, clinical pathology) to ensure overall health and to monitor for any potential age-related changes.
The aged rhesus colony at the Center provides distinctive opportunities to better understand normal aging changes and to develop new treatments and solutions for age-related health problems.
In the wild, rhesus monkeys thrive on fruits, seeds, roots, herbs and insects. In captivity, monkeys primarily eat monkey chow, and an array of fresh, seasonal fruit, vegetables and nuts once to twice a week to provide them with variety and to supplement their diet (photo below). Outdoor monkeys also forage in the grass for roots, seeds, and insects, and are provided with a daily mixture of seeds and oats scattered in the grass to replicate normal foraging behaviors. Indoor animals also receive seeds, oats, and fresh fruits and vegetables, in addition to monkey chow and specialize enrichment foods.
SPF means “specific pathogen free.” SPF monkeys are free of specified infectious agents, including herpes B virus, type D retrovirus, simian immunodeficiency virus (the monkey form of HIV) and simian T-lymphotropic virus. Not only can these pathogens interfere with research results, monkeys carrying them pose risks to researchers and animal care staff. Certain types of AIDS research, in particular, require SPF animals. The CNPRC is striving to expand its SPF breeding colony for the health of the animals and the safety of Center personnel.
The CNPRC is a research facility and is not open to the general public. This is because humans may carry diseases that can be extremely dangerous to the monkeys. Diseases carried by both humans and monkeys may also be fatal if contracted by the other species. All CNPRC employees are subject to annual health screenings to ensure they do not place the animals at risk of contracting human disease. The Center’s veterinarians, animal care staff, and scientific staff are all trained extensively in the appropriate safety procedures and ensure the prevention of the transmission of diseases.
Research at the CNPRC is focused into four primary areas:
Behavior and neuroscience
Infectious diseases and immunology
Reproduction and regenerative medicine
Respiratory biology and disease
AIDS research is one area of infectious disease research and includes studies related to pediatric AIDS, vaccine development, and mechanisms of virus transmission. Other infectious diseases include cytomegalovirus (CMV), and studies on Helicobacter pylori. Investigators also study toxins in the environment that are considered “endocrine disruptors” and can alter reproduction. New stem cell and gene therapies are being studied for blood diseases, such as hemophilia, and other disorders such as Pompé disease. New tissue engineering approaches to replace kidneys and tracheas damaged by disease are also under study. UC Davis and the CNPRC is home to a large, interdisciplinary pulmonary research team that studies the biology of both healthy and diseased lungs, specifically the effects of air pollutants and particulates, and the relationship between these contaminants and childhood asthma. Another research focus is the study of the physiological and health effects of chronic stress. The CNPRC is involved in research related to Alzheimer’s disease, methods for healthy aging, and autism, among many others. Please see Our Science for more information.
All research is conducted humanely under strict compliance with the Animal Welfare Act, which governs laboratory animals are housing, care and use in investigational studies, and according to IACUC review and approved protocols. The law requires that any procedures causing more than slight or momentary discomfort be performed using appropriate pain-relieving drugs, and requires the use of anesthesia for surgical procedures, comparable to humans. It also stipulates that animals be euthanized during or after a procedure if they would otherwise endure chronic pain.
Primate Center veterinarians and scientists are dedicated to ensuring that animals involved in research projects are provided with the best care and research conduct according to approved IACUC protocols. Veterinarians also provide routine health care, including regular physical exams and dental cleaning and care.
Studies require prior review and approval by the UC Davis Institutional Animal Care and Use Committee (IACUC), which ensures that the project meets all federal laws governing animal care and use. The CNPRC is part of the UC Davis Animal Care Program which is accredited by the Association for Assessment and Accreditation of Laboratory Animal Care International (AAALAC), a private, nonprofit group that promotes the humane treatment of animals in science through voluntary accreditation. UC Davis is one of more than 770 research institutions and other organizations in 29 countries worldwide that have earned AAALAC accreditation, demonstrating the program commitment to responsible animal care and use.
Not all of the CNPRC monkeys are involved in research studies; some are used exclusively for breeding. The outcome for a monkey upon conclusion of a research study is dependent on the type of study and whether the monkey was part of a “control” group. A control group in a study serves as the basis of comparison when assessing the effects of a treatment, and members of a control group often receive no treatment, a “usual” or “standard” treatment or a placebo. Animals serving as controls may be returned to the breeding colony or assigned to another experiment. However, in some cases, animals involved in research studies must be humanely euthanized upon completion of the study to allow the analysis of the effects of a disease or a treatment on the animal’s tissues. This provides critical information directly relevant to humans.
Proposals for research studies involving monkeys must be reviewed and approved by the UC Davis Institutional Animal Care and Use Committee (IACUC), which ensures that the project meets all federal laws governing animal care and use. Projects are also reviewed internally by the CNPRC Research Advisory Committee.
The CNPRC is a part of the UC Davis Animal Care Program which is accredited by the Association for Assessment and Accreditation of Laboratory Animal Care International (AAALAC), a private, nonprofit group that promotes the humane treatment of animals in science through voluntary accreditation. UC Davis is one of more than 770 research institutions and other organizations that have earned AAALAC accreditation, demonstrating its commitment to responsible animal care and use.
In addition, the CNPRC has regular, unannounced inspections by the U.S. Department of Agriculture, as required by the Animal Welfare Act passed by Congress in 1966.
UC Davis also follows NIH guidelines for the care of laboratory animals and is also inspected by the NIH Office of Laboratory Animal Welfare (OLAW). Following their 2013 inspection, OLAW praised UC Davis and the CNPRC for its “outstanding animal care and use program.”
Throughout its 55-year history the CNPRC has been a leader in quality animal care and is continually making advancements in the care and well-being of captive primates. Its outstanding animal care program has been recognized by OLAW and AAALAC, both organizations with high standards for animal facilities. The CNPRC was inspected by both these organizations in 2013.
The USDA conducts regular rigorous inspections of the primate center. These inspections serve to monitor compliance with all rules and regulations relating to animal care, and to create an environment where animal care technicians provide the best care possible.
There have been violations at CNPRC in the past, as there have been at every other national primate center. At CNPRC, these violations have involved small numbers of animals and have rarely led to fines.
The university is committed to the highest ethical and medical standards for the care of its animals. Any violations, as rare as they may be, are addressed immediately and comprehensively and are promptly reported to regulatory oversight entities as required. New procedures are developed to minimize the chance of recurrence.
The UC Davis Animal Care Program is constantly working to eliminate the potential for violations and maximize the well-being of all animals at UC Davis. The CNPRC also conducts research that aims to improve the quality of life for the animals under its care.
The center has multiple security measures in place to keep the monkeys safe. All housing facilities are monitored daily to ensure that the animals are secure. UC Davis reported one event to the USDA in 2011 where some monkeys exited their outdoor enclosure but due to multiple security measures, all were secured on the premises and all were safely returned to their enclosure.
Infectious diseases that are studied at the CNPRC are carefully controlled and all personnel are appropriately trained to ensure containment of biohazards. PPE (personal protective equipment) is worn at all times when around the animals, to ensure protection for the humans and animals. Humans carry infectious viruses and bacteria that can be transmitted to the monkeys, therefore all personnel that work at the CNPRC are screened annually and wear PPE to protect themselves and the monkeys.
The CNPRC does not conduct research on diseases such as the Ebola virus or anthrax related studies.