Primates
References and
resources for this tutorial:
Jeffrey D. Fortman, Terry
A. Hewett, B. Taylor Bennett, The Laboratory NonHuman Primate (A
Volume in The Laboratory Animal Pocket Reference Series) (Boca Raton: CRC
Press, 2002)
James G. Fox, Lynn C.
Anderson, Franklin M. Loew, Fred W. Quimby, Editors, Laboratory Animal
Medicine, 2nd Edition, (New York: Academic Press, 2002) chapter
on “Nonhuman Primates” by Bruce J. Bernacky, Susan V. Gibson, Michale
E. Keeling, and Christian R. Abee
F. Barbara Orlans, Tom
L. Beauchamp, Rebecca Dresser, David B. Morton, John P. Gluck, The Human
Use of Animals: Case Studies in Ethical Choice (New York: Oxford University
Press, 1998)
Trevor Poole, Editor;
Pauline English, Editorial Assistant, The UFAW Handbook on the Care
and Management of Laboratory Animals, 7th Edition, (London:
Blackwell Science, 1999)
Overview
Using primates as
research subjects has a unique history in the topic of animals in
science. While their closeness to us (a range of 95-98% genetic similarity
in the case of the Great Apes) is what makes them valuable biomedical
research subjects it is also a cause for ethical discomfort. Some of
the projects using primates have led to greater public argument
over their role in research. Their value as research subjects has lead
to increased legal protection for them. Some people say that the genetic
closeness of the Great Apes should not only exempt them from use as research
subjects, but also affect their moral standing. The Body Group
Papers on The Use of Non Human Primates in Research in Research and Testing
(2002) is an example of one of the current discussions concerning
primates and research ethics.
In 1994, Deborah Blum’s The
Monkey Wars (Oxford University Press) was published and became a
popular trade book. The author, a well-known science writer, had received
the Pulitzer Prize for the series of articles she had written for the
Sacramento Bee and these articles became the impetus for the book which
is listed in the Science/Current Affairs titles for Oxford. The listing
points out the public’s keen interest in matters of science, to the point
that science is considered
a topic in current events. Moreover, it indicates that concern for other
species, especially primates, is increasingly a matter for general societal
discussion.
As it stands now, Blum explains, the research community and
its activist critics are like two different nations, nations locked in a
long, bitter seemingly intractable political standoff…But if you listen hard,
there really are people on both sides willing to accept and work within the
complex middle. When they can be freely heard, then we will have progressed
to another place, beyond this time of hostilities. In The Monkey Wars,
Deborah Blum gives these people their voice. (Business Week, back cover of
paperback edition, Oxford University Press, 1994) (For an interesting internet
roundtable discussion with Deborah Blum see: Deborah
Blum on “The Monkey Wars.”)
Adding
to the complexity of the basic ethical questions about animal subjects
in research is the
different status of the varying primate populations world-wide in terms
of their survival in native habitats, ranging from thriving to vulnerable
to threatened to endangered to nearly extinct. For example, the rhesus
macaque is a monkey with a wide range, thriving in their native habitat
while the sooty mangabies are almost extinct in their native land. The
Duke Primate Center is one research center which works with the country
of origin, in this case Madagascar, in prosimian conservation efforts.
The goal of the Center is directed toward the primates themselves, not
their use as biomedical subjects. The
International Primate Protection League is a well known international
organization with a wide range of activities.
In response to this problematic
status in their native habitats, almost all primates used in research are
now from captive breeding programs. In addition, there are moratoriums
on some breeding programs involving chimpanzees in this country due to
the current large population of laboratory chimpanzees.
The use
of chimpanzees (Pan troglodytes) in biomedical research has led
to numerous medical advances, including the development of a vaccine for
hepatitis B virus. In 1986, chimpanzees were thought to constitute the
critical model for understanding the human immunodeficiency virus, and
a breeding program was established to provide animals for the study of
this virus. The breeding program was very successful, and the combination
of an increase in chimpanzee numbers and less-extensive research use than
was expected has created a surplus of chimpanzees and a substantial management
problem. Although chimpanzees are available for research, there are also
pressures not to use them, such as the high cost of housing and maintenance
and their endangered status in the wild. Their close genetic relationship
to humans, which makes them the appropriate surrogate for human-health
research, also creates serious concerns about the ethics of their use by
scientists and the public. The US federal government now owns or supports
some 900-1000 chimpanzees at a cost of approximately $7.3 million per
year, but government investigators pay "use fees" for using
animals in government research. Each of those issues contributes to the
cost to
investigators and the complexity of using chimpanzees in research. (Executive
Summary, p. 1, Chimpanzees in Research:
Strategies for Their Ethical Care, Management and Use, National Academies
Press, 1997)
Another recent National
Academies Press book, International Perspectives:
The Future of Nonhuman Primate Resources, reports
on an international workshop to discuss this complex problem. A Few New Developments in Primate
Housing and Husbandry, an online article by Steven J. Schapiro, discusses
changes in the Rhesus macaque and chimpanzee breeding program at the MD
Anderson Cancer Center in terms of specific pathogen free status.
Currently, according
to the United States Department of Agriculture (2000), there are 57,000
non-human primates in
research in this country. Although not every university research program
uses primates, most major medical schools and research institutions do
use primates to varying degrees. Due to various reasons, they are quite
possibly the most complex animal subject used in research and as such,
this tutorial is a summary of the major areas of interest including clearinghouse
information. One of the most extensive resources for primates on the web
is the Primate Info Net, managed by the
Wisconsin Primate Research Center, one of the eight national primate
centers in the United States.
As laboratory animals,
primates are in a class by themselves. As the animals most closely related
to humans, phylogenetically, physiologically
and anatomically, they have important uses in research. However, this relationship
is also the reason that there is currently much discussion about the use
of primates and how they are maintained in captivity. They are also expensive,
to breed, rear and buy. All primates are listed by CITES (Convention on International Trade in
Endangered Species of Wild Flora and Fauna) (1975-1996), and trade is therefore
controlled. Exportation of wild primates from habitat countries for research
purposes causes a depletion of wild populations, and involves both conservation
and welfare issues. A useful document covering the capture, transport and
housing of primates has been prepared by the International Primatological
Society (1993). (The UFAW Handbook on the Care and Management of Laboratory
Animals, 7th Edition, op.cit. p. 537)
Primates vary immensely
according to genus and species (there are 233 different species of primates);
those used in research are sub-order “Anthropoidea” the monkeys, which
are usually divided up into two infra-orders, the Catarrhine, old world
monkeys (from Africa and Asia), and the Platyrrhine, new world monkeys
(from Central and South America). Although the common names are more familiar,
data bases may use the latin names in their search engines so we include
both of them here.
Old World Monkeys (OWM)
Monkeys
in this group include guenons, macacques, baboons and mangabeys. Monkeys
in this group
are large (20 to 50 pounds), ground dwelling, omnivorous; they forage for
food over wide open territories. Some, such as the Asian macaques and
African mangabeys are more tree-dwelling. Their tails are not prehensile,
they have narrow noses, ischial callosities (an evolutionary development
that helps them sit on surfaces for long periods of time), have sexual
skin that changes color/shape, have opposable thumbs; they do not need
supplemental vitamin D, often have cheek pouches and often the males and
the females have different physical characteristics.
The most common Old World
Monkeys from Asia used in research are the macques. such
as the
crab-eating macaque, also called the cynomolgus monkey
and Macaca mulatto or rhesus macaque.
The most common species
of OWM from Africa used in research are the baboon (Papio anubis, Papio
cynocephalus ) the guenons and
the mangabeys.
Guenons are smaller, tree-dwelling monkeys; the most common laboratory
species is the African green monkey or Cercopitheecus aethiops. The mangabeys
most used are sooty mangabeys, Cercocebus torquatus atys.
The larger primates used,
such as chimpanzees,
belong to the Pongidae family, the great apes.
New World Monkeys (NWM)
The NWM can be divided
into two families, the Callitrichidae and
the Cebidae. The former include marmosets and tamarins and
the latter the howler,
woolly, spider, owl, capuchins and squirrel monkeys.
NWM have flat noses, all have tails of which some are prehensile, they
are long limbed and lack ischial callosities—both characteristics of their
tree-dwelling nature. They have long nails, do not have opposable thumbs
or cheek pouches and require supplemental vitamin D. They do not show sexual
skin changes and the males and females have similar physical characteristics.
The most common NWM used
in research is the squirrel
monkey, Saimiri sciureus. A recent issue of the ILAR journal (Volume
41, 2000) focused on The Squirrel Monkey
in Biomedical and Behavioral Research.
Both OWM and NWM share
general characteristics such as being extremely dexterous, highly visual,
with a long gestation and post-natal period. They have a long period of
puberty due to the fact that much of their behavior is learned and not
instinctive. They are social animals, with highly developed group dynamics.
Housing and environment planning must take into account their need for
interaction with conspecifics. Because they are highly intelligent and
can be aggressive, they need careful and trained handling. Facial expressions
are indicators of different states of arousal; for example, aggression
is indicated via staring and open-mouthed teeth showing or yawn display.
An open-mouthed “smile” is a sign of fear. Primates that turn their backs
toward others are showing submission, whereas the shaking of bars, or bristling
out of hair is a threat display. Staring directly at a primate should be
avoided as it will be perceived as a threat. In any colony Zoonotic concerns,
both to protect handlers from primates and to protect primates from handlers
need to be addressed.
The Animal Welfare Institute’s Comfortable
Quarters for Non-Human Primates in Research Institutions presents
a good summary, with photos, of basic husbandry issues relevant to primates
in general.
Primates and
science
Currently, there are
eight National
Primate Research Centers in the United States, as well as a number of other primate centers
and colonies. A Brief
History of the Regional Primate Research Centers is an historic overview
of the founding of primate centers in the United States. For an overview of the range of
current research using primates, see Primates in Biomedical
Research.
An historical review
of some of the major use of primates as research subjects is, in some cases,
an example of the continuing argument over the use of animals, particularly
primates, as research subjects. In reading through this selection of brief
summaries of some of the more publicized use of primates in scientific
research, ethical principles such as costs and benefits, who benefits,
who decides, acceptable and unacceptable risk, vulnerable populations,
and setting limits continually face us. There is also the dilemma of the
incremental nature of scientific discovery where blind alleys and mistakes
are part of the process; one can wonder if there is any way to include
this reality in the ethical calculus. A recent policy statement from the European Union Scientific
Commission comments on the complexity of using primates in research.
With the research
into polio and the search for a vaccine, primates were in demand;
during the period of most intense research, 1953-1960, mortality for
monkeys used in vaccine development approached the 1 million mark. This
included the numbers dying either in transit or shortly after, before
being included in research protocols. (Rudacille, 2000 and Rowan, 1984)
The high numbers concerned the government of India,
the major exporter of the monkeys to the United States and
it was at this time that the beginnings of captive breeding programs
were begun in the countries of
origin.
During this period of
time, the rising expertise of biotechnology also had a role in polio research.
The polio virus’ preferred place of growth was the primate kidney: labs
began to produce cell lines of primate kidneys to grow the virus, thereby
reducing the need for a “whole monkey.” There is currently a debate about
the historic use
of primates in polio research; those opposed to using animals as tools
for biomedical research argue that using animal models for human diseases
actually set the research back due to the difficulty of correctly extrapolating
from an animal model.
Another area where Primates, due
to their biological closeness to us, have been used extensively is in space research. A major project
was the joint project of American/French and Russian scientists, the Bion project, which studied
among other things, the phenomenon of weightlessness. In 1997, NASA suspended its
part in the Bion primate research program, in large part due to public
concern and ethical questions about the use and welfare of the rhesus monkeys
in the program.
In the 1980s, the use
of primates in nerve studies, particularly the research by Dr.
Edward Taub became highly publicized. Dr. Taub was using the deafferentation,
a procedure that severed nerve connections, to study the ability of nerves
to regenerate. The
Silver Springs Monkey Case, gave PETA, a newly formed animal rights
group at the time, a large public hearing. There is no question that spinal
cord research is ethically troublesome and that the animals used are paying
a high cost.
There is no question
that Primates have a unique place in brain
research, again, due to the genetic closeness to humans. Questions
such as how to conduct ethical research in areas that involve the nervous
system are very challenging. How far should we go? How do we (and who should
the “we” be?) decide what limits should be set, both in terms of the questions
we ask, and the difficulties the animals undergo?
Primates, again, due
to their phylogenetic closeness to humans, have been used extensively in
behavioral research. One of the kinds of studies have been maternal deprivation
studies—such work has also been done with rats and dogs--the work of Harry
Harlow is probably the best known. Harlow was working in the 1950s;
one of his goals was to show scientific “proof” of the critical nature
of the
maternal-infant bond on future psychological development. His work with
rhesus monkeys, along with other scientists on attachment studies were
major developments in the field of psychology. Although the work he did
obviously caused great suffering for the monkeys used—nobody questions
this either now or then—it did help revolutionize child care in this country.
Harlow was also one of the first researchers to experimentally show the
high level
of intelligence and learning ability
in primates.
The historical context in which Harlow’s work proceeded is also
important. He was an early soldier in the profession of experimental
psychology’s campaign
to be acknowledged as a natural science. This acknowledgement was judged
to require the adoption and application of a strictly scientific methodology,
then widely interpreted to mean the explicit use of experiment and controlled
observation. …Harlows hypothesis was controversial for a number of reaons….the
typical learning experiment required that the animals be placed on some form
of deprivation (e.g. food or water) so that the learning would take place.
…He described monkeys as having complex cognitive abilities that involved
the existence of intentions, curiosity, and solution plans…Harlow’s experiments have also
revealed a great deal about the cognitive and emotional life of monkeys.
…When reviewing Harlow and his work we should recall the
assumptions of the period in which the work was done. The Animal Welfare
Act did not exist until 1966 and did not directly influence experimental
designs until 1985. (“Monkeys Without Mothers, in Orlans, et. al. op. cit.
pp. 174-185)
There have been critiques
of the primate attachment studies over the years, another example
of the ongoing debate over primates as scientific research subjects. Deborah
Blum has recently authored, Love at Goon Park and the
Science of Affection, a biography of Harry Harlow that discusses
this question of the ethical problems when the research is in question
is attempting to prove a new hypothesis.
During the 1970s to 1980s
chimpanzees and Bonobos were research subjects in language
and cognition studies, many of them ongoing today. Beginning in the
1970s, R. Allen Gardner and Beatrix T. Gardner, a research team at the
University of Nevada were involved with teaching ASL language to Washoe,
a chimpanzee. Roger Fouts, who had
begun work with the Gardner’s as a graduate student later moved Washoe
to Central Washington University where a colony of chimpanzees still live;
the public has become involved via the Friends of Washoe organization,
providing financial support and publicity. The Chimpanzee and Human Communication Institute was
founded in 1992.
Continuing work on ape
language by Sue Savage-Rumbaugh, Duane Rumbaugh as well as others goes
on at the YerkesPrimateCenter and at the Georgia State Language Research Center.
The level of achievement by the primates raises ethical questions regarding
their treatment by us and their moral standing.
Do the great apes’ apparently exceptional capacities for
thought and emotion justify conferring higher moral value on them than on
other nonhuman species? One response is that the richness of the apes’ mental
lives makes them more aware of and more distressed by the pain, suffering,
or discomfort they experience from being confined in a sterile environment
or deprived of opportunities to form relationships than is experienced by
less cognitively complex creatures kept in such conditions. Members of the
US Congress seemed to rely on a version of this position when they enacted
a statutory provision that laboratory primates (and no other species) must
be given “a physical environment adequate to promote [their] psychological
well-being. (Orlans, op.cit. p. 151)
This
year, "The
Great Ape Project," edited by Paola Cavalieri and Peter Singer
was published. It is more than a collection of essays by 34 psychologists,
biologists, philosophers, ethicists, and anthropologists. It is also
the launching of the Great
Ape Project which hopes to begin a movement with the purpose of giving
apes the same legal rights as children and mentally retarded adults.
Apes would
no longer be objects, things, or chattel, but considered as persons. The
argument is that apes have both the ability to relate with others and to
demonstrate consciousness. For example, DNA studies show that a chimpanzee's
closest relative is not the gorilla, but the human. Humans share 98.4%
of their DNA with the two living species of chimpanzees. Studies of the
great apes have shown emotional and social lives similar to humans, for
example, lifelong ties with family members. Washoe, the chimpanzee and
Koko, the gorilla have shown capacity for speaking English and using abstract
concepts through sign language and have demonstrated self-consciousness
and abilities previously thought to only be present in humans. (The
Great Ape Project)
Interestingly enough,
a case could be made that the Great Ape Project is yet another stage
in the evolving ethical thinking about animals, a direct result of the
scientific research that has demonstrated the high level of cognition
that the Great Apes are capable of.
Biology and Husbandry
Old World Monkeys (Macaques,
Baboons, African Grey Monkeys)
OWM are both terrestrial
and tree dwelling; in the wild they sleep in the trees but roam on the
ground. Laboratory housing should provide both extended floor space as
well as perches. Optimum temperatures are 15-24 Centigrade with humidity
at 45-65% and 12-15 air exchanges per hour. Their natural instinct is to
go up and look down on “intruders;” caging should be tall enough with high
perches to allow for this normal behavior pattern.
Biological
and chemical perimeters vary widely between species and individuals.
For example, the
heart rate for a Rhesus macaque can vary between 120-180 while the Cynomolgus
macaque’s heart rate measures 240 bpm (data from Wolfensohn & Lloyd
for anesthetized animals). Primates show great variety between species
(e.g. the Cynomolgus will be easily stressed by routine events where the Rhesus will
be less traumatized) and between individuals of the same species. Any housing
situation needs to take into account this range of personalities. In the
group housing situation hiding places, perches and visual barriers should
be available to allow for subordinate animals to avoid direct confrontation.
Likewise, food items should be placed in different areas to allow lower
ranking animals to eat without having to compete. If J-feeders are used,
they should be inspected to be sure any biscuit food drops down; if any
of the primates are debilitated or less dexterious they may be unable to
remove food from these feeders.
Some form of group housing
is preferable; even quarantined animals should be pair housed if
at all possible. If a primate needs to be singly housed some form of
contact, e.g. adjacent caging to enable pairs to groom each other, should
be attempted. Macaques are often caged in large groups, indoors or out.
All primates have specific social hierarchies; the exact patterns vary
with species but care must be taken in introducing new individuals. Macaques
can be group housed with several males and females with offspring, while Baboons do better grouped
per family, with one male and one to four females with offspring. The
young stay with their parents until adults since there is a prolonged period
of juvenile learning and socialization.
Commercial pelleted feed
is usually supplemented with a variety of items, for example, fresh fruit,
nuts in the shell, seeds, boiled eggs in the shell and/or pine kernels.
Primates need supplemental vitamin C. Food should be offered at least twice
daily to avoid bloat; since in the wild primates spend the majority of
their time foraging for food, it is preferable to provide some sort of
foraging experience. Methods to do this vary, from presenting “foraging
trays”, shavings mixed with food items, to providing shavings as bedding
with food items randomly placed in the bedding. Foods and treats can be
placed in containers or hidden in “puzzle boxes." Using
Inexpensive Feeding Equipment and Techniques for Primate Enrichment, an
online article, has some concrete suggestions. An added advantage is that
the increased foraging gives the primates a sense of control over their
environment, as well as providing a greater degree of variability to their
day. Baboons will also eat small insects, grasses, roots and lizards. Cynomolgus
macaques (often called crab eating macaques) also eat crustaceans. Water
should be freely available.
New World Monkeys (Marmosets,
Owl monkeys, Tamarins, Squirrel monkeys)
Since these primates
are arboreal in the wild, caging needs to be tall with an emphasis on quality
vertical space rather than floor space with room for normal postures, e.g.
perching with the tail extended down naturally instead of draped on the
floor. As with the OWM, their instinct is to go up and look down. Since
their wild habitat is the rainforest, temperatures should range between
20-28 degrees Celsius with humidity at 55-65%. Either ultraviolet lighting
should be available for them to convert vitamin D2 to D3 or they need to
have supplemental vitamin D3 added to the diet. If they are overcrowded,
they are highly susceptible to disease. Marmosets do
best housed in family units, an adult pair with offspring.
Nesting boxes are important
for body heat conservation, especially with the smaller primates; metal
caging will predispose them to heat loss. The boxes should be made of wood
to conserve body heat. PVC for perches and caging materials is preferable
to metal. Marmosets and Tamarins scent mark their territory; this
is normal behavior so cleaning schedules should take this into account,
since
removing the territorial markers will be stressful to the primates, and
cleaning should be done on a rotating basis so as to leave some of the
marked areas untouched. Nest boxes in particular should remain as undisturbed
as possible, e.g. rotating only some of the wooden perches for cleaning
at a time. In many cases these boxes can be used as transfer “cages.”
Squirrel monkeys do better
with a harem system of caging since the males are interested in the females
only during breeding and both sexes prefer same sex same age conspecifics.
They do not engage in mutual grooming as do most other primates but they
do sleep together in a huddle. One method of housing is to allow the males
to join the females and offspring during breeding periods; the rest of
the time, the males are caged with conspecifics and the females kept with
their offspring. Stable hierarchies form quickly with Squirrel monkeys
but they still need to be checked frequently for fighting in the first
few days they are placed together until the hierarchy is clear. It is important
to provide areas for them to withdraw from each other.
As
with OWM, pelleted feed is common with supplements of fruits, nuts and
seeds. For NWM, the
feeding stations should be elevated, since a behavioral trait is to inspect
the food, drop it down and then go and retrieve it to eat. Again, flooring
should allow for this. If feces and debris are not cleaned at least once
daily, the dropped food will be contaminated and remain uneaten—in cages
with wire bottoms the food will drop through and the monkeys’ health will
be compromised due to inadequate amounts of food eaten. Since they have
need of a high calorie diet and are prone to hypoglycemia, they should
be presented with food at least twice daily.
The National Academies
Press has an online book, Nutrient Requirements of Non-Human
Primates, 2nd Edition.
General issues of primate well-being
Nonhuman primates have
extremely complex social needs and
foraging behaviors and housing should allow for species specific behaviors
such as mutual grooming. Special attention needs to be paid to the specific
groupings; e.g. they do better if housed with unfamiliars since this reduces
the cliques and tendency to form groups against “outsiders.” They should
be monitored closely until the social hierarchy is established, crush and
bite wounds may not be readily apparent. Any individuals that seem depressed
or solitary should be immediately removed and checked for wounds. Even
after the hierarchy is stable, they should all be checked to be sure the
nutritional status is satisfactory for even the low ranking individuals.
Pair housing needs to be done carefully; the usual method is to allow possible
pairs to familiarize with each other via open mesh screening for a period
of time before grouping together. The key is to identify a pair that is
comfortable together. If for any reason pair housing is not possible, then
visual and auditory contact should be maintained and if at all possible,
mutual grooming through cage openings should be facilitated. Often primates
are shipped in pairs so that quarantine periods are not solitary.
They require significantly more enrichment than other species.
According to the Research Animal Resources Website from the University of Minnesota, a primate
enrichment program should consist of the following components:
1. Opportunities for
social interaction, including housing in compatible pairs, visual contact
with
other nonhuman primates and socialization with the animal
care technician and veterinary technician.
2. Foraging opportunities, such as provision of special "food treats",
use of puzzle feeders and foraging boards.
3. Environmental manipulanda such as toys, chew sticks, perches, swings and
an exercise cage.
4. Visual and auditory stimuli through videos and television
Enrichment procedures
are varied regularly with nonhuman primates to ensure that the activity
is novel. Investigators are encouraged to participate in
the enrichment program. However, they should consult with the veterinary
staff to ensure that efforts are coordinated and that animals do not receive
articles that may be dangerous or excessive amounts of "treats" that
could interfere with their normal diet. (http://www.ahc.umn.edu/rar/acservices.html#Routine)
The use of wood chips for
enrichment has several benefits. The use of bedding increases sanitation
and makes cleaning easier; the animals are also able to keep themselves
cleaner, dryer and warmer if provided with bedding. Also, increased opportunities
for foraging reduces stress and thus experimental variability is decreased.
This study shows that
when deprived of the opportunity to forage, monkeys compensate by increasing
other behaviours; our young group showed increases in play, aggression,
manipulation of the environment, and abnormal behaviours, primarily self-aggression.
A litter substrate reduces these behaviours and encourages foraging,
even in the absence of grain. In another study we have also shown that
the beneficial effects of deep litter:
a. generalize
to other primate species, and
Environmental Enrichment
for Primates an Annotated Database on Environmental Enrichment and
Refinement of Husbandry for Nonhuman Primates is available and contains 477 online
articles.
In general, primates
are either purchased from vendors who have their own breeding programs
here in the United States or are
bred in the institutions doing the research. One of the issues here is
how best
to maintain them since
in the wild they live in family units long after the neonates are grown. Artificial Weaning
of Old World Monkeys: Benefits and Costs, addresses this procedure
of weaning the young from their mothers.
The topic of psychological well-being is complicated with
discussion over what is the proper definition.
Psychological
well-being refers
to mental state. It cannot be defined in terms of the environment, although
environments certainly influence individual well-being. It cannot be
equated with an activity or behavioral profile, although individual status
influences behavior. It is not synonymous with any physiological state,
although physiological condition and psychological well-being interact.
Psychological well-being is influenced by meeting the needs of an individual
animal that are based on its species, sex, age, and developmental experiences.
Its assessment must be based on multiple indexes:
The
animal's ability to cope effectively with day-to-day changes in its social
and physical environment (with reference to meeting its own needs).
The
animal's ability to engage in beneficial species-typical activities.
The
absence of maladaptive or pathological behavior that results in self-injury
or other undesirable consequences (see Bayne 1996 for a discussion of
the normal and abnormal behaviors).
The
presence of a balanced temperament (appropriate balance of aggression
and passivity) and absence of chronic signs of distress as indexed by
the presence
of affiliative versus distress vocalizations, facial expressions, postures,
and physiological responses (e.g., labored breathing, excessive cardiac
response, and abnormal hormonal concentrations).
The
assessment should be based on the behavior of an individual animal …
(National
Academies Press: The Psychological
Well-Being of Non-Human Primates, 1998)
Major illnesses
An index from the Wisconsin PrimateResearch Center lists articles
on different illnesses of primates.
A sample vaccination
schedule has been published by the Primate Research Center, University
of Washington.
Zoonotic diseases
Due to the phylogenetic
closeness, disease risks go in both directions, non-human primates to people
and vice versa. Primates are at risk for
many of the same diseases that we are, e.g. colds, flu, tuberculosis, mumps,
herpes simplex and hepatitis. If a worker has a cold they should wear a
face mask and check with the veterinary office as to any other precautions.
Primates, especially OWM, are extremely susceptible to measles; if
workers have been exposed (e.g. their children are ill with measles or
are in school with classmates who have become ill) then they should check
with their veterinary office as to the correct protection for the colony.
Salmonellosis is another illness of concern, as are Shigella and Campylobactger
yersinia.
Tuberculosis testing is routine
for monkeys; it is highly contagious within a colony and a sick individual,
monkey or person is a potential carrier to others.
The disease of most concern
in terms of spread from primate to person is Herpes
B; (Cercopithecine Herpesvirus 1) it
is so common among Macaques that most institutions consider all Macaques
to be potential carriers, shedding the virus in mucous membrane secretions.
Mouth lesions are the most common symptom of this illness in primates.
This illness has a fatality rate of 70% for people. Purpose bred primates
are preferable, from a known vendor; this is why many institutions also
have their own breeding programs. A common behavior of primates is to spray
their saliva as an aggressive display: this is one of the reasons protective
clothing is standard for those working with primates. The risk of Herpes
B is one of the reasons primates are not handled directly.
Other viruses have been well publicized;
primates can carry viruses such as Marburg and Ebola.
Handling and
procedures
Because of their phylogenetic
closeness to us, zoonotic concerns are paramount, both from primates to
us and from us to primates. It is standard procedure that animal caretakers
wear protective clothing including masks and gloves to prevent disease
transmission. Yet, primates, both human and non-human rely on facial visual
cues for communication. For monkeys, a masked human being is frightening
since they cannot see visual cues. The benefits of acclimating and training
primates to participate in simple, common procedures are many, e.g. reduced
stress will standardize chemical panel perimeters. Increasingly, there are protocols
to train primates to cooperate for simple procedures such as injections
and medication. http://www.brown.edu/Research/Primate/current.html#syringe
Before many procedures
though, most primates are sedated. For OWM, chemical immobilization with ketamine is
normally used. Injections can be given to a confined animal with the help
of a squeeze cage. Once sedated, the monkey can be held by the upper arms,
facing away from the handler. Small NWM can be caught and hand restrained
(by personnel wearing protective gloves and clothing) and then sedated,
usually with alphaxolone/alphadolone. Physical restraint of
a conscious animal should only be attempted by trained, experienced personnel.
Animals may be pole and collar trained if they will be handled frequently.
Tether systems are recommended if animals must be administered drugs or
if blood
must be collected frequently. The University of Minnesota Research
Animal Resources has posted their procedures to follow in case
of a bite or scratch as well as specific instructions concerning handling
at http://www.ahc.umn.edu/rar/handling.html#PRIMATE.
Nonhuman primates present a variety of challenges for human
handlers. Nonhuman primate behavior is extremely complex. Proper behavioral
and handling techniques are essential to prevent excessive stress to the
animal that can be manifested violently. In addition, because of the close
phylogenetic relationship between human and nonhuman primates, a variety
of diseases can be transmitted back and forth. To protect both the animal
and the handler, as well as other humans the handler may contact, proper
preventative protocols must be followed. These include semi-annual tuberculosis screening, use
of protective clothing and
familiarity with procedures to
follow in case of contact between nonhuman primate body fluids and exposed
human tissue, such as with a bite or scratch, or an eye splash. Training
in these biosafety procedures and in proper handling and behavioral techniques
is required before nonhuman primates may be used. (University of Minnesota: http://www.ahc.umn.edu/rar/vetservices.html#Training)
"Working
Safely with Nonhuman Primates" was produced by the NIH Office
of Animal Care and Use in 1999 for training staff in the NIH intramural
research
program. This video has a strong emphasis on proper use of personal protective
equipment combined with understanding nonhuman primate behavior, and
the general principals are applicable to any program that houses nonhuman
primates.
Monitoring
As with all animals,
hiding pain and discomfort is instinctive. Monitoring should be done on
a daily basis, ideally several times a day, by people familiar to and with
the monkeys so that a change from normal will be quickly perceived. It
is best to view the colony out of sight at first to view their appearance
and behavior when they think they are unobserved. Then follow a standard
inspection procedure, checking for signs of weight loss (or gain), for
a normally groomed coat and for abnormal discharges. A monkey that is isolated,
less active or unusually quiet should be removed from the group for a thorough
medical check. A monkey in pain will have a sad look on his/her face, sometimes
the eyes may appear glassy. They will clench their teeth, grimace or be
unusually restless. Alternatively, they can be less active, huddling with
their arms across their bodies. Sometimes the others will give an ill monkey
increased attention and grooming and at other times, attack. Thus, an ill
monkey should be removed promptly from the group. They usually do not vocalize
when ill or hurt; vocalization is usually a sign of anger and/or aggression,
not pain. All facilities will have their own health
monitoring protocol for colonies.
Current
research using primates
Marmosets are susceptible
to oncological viruses and infectious hepatitis. They are used in immune
system research.
Monkeys are used for malaria
research.
They are used in HIV and AIDS vaccine research.
Squirrel monkeys are the
most commonly used of the NWM; for many studies they are considered the
representative model for primate biology. They are used in vaccine and
general pharmacological research, malaria research and toxicology studies.
They are susceptible to Creutzfeldt-Jakob disease and other transmissible
spongiform encephalopathy illnesses. They have a hyperactive sympathetic
nervous system and are often used to study atherosclerotic disease.
Primates have historically
been used for both toxicology studies and for pharmacological work, particularly
in the development
of vaccines. Increasingly, they are the final step for much of the
testing with rodents used in the earlier stages as a general biological
model and the monkeys used as a primate model, prior to clinical trials
with people.
Given
the ethical issues which surround animal experimentation, it is important
to be aware that due care for the biostatistical aspects of experiments
can contribute greatly to the humane conduct of research, by minimizing
the exposure of animals to harm. Suppose that an experiment is planned
which would incontestably settle a physiological point having great bearing
on the relief of human suffering. Suppose further that there really were
no scientifically valid substitutes for animal testing in that particular
case, and that the animals were truly to be treated as well as possible
given the experimental protocol. This may indeed be a lot to suppose.
But would it necessarily follow that the experiment would be as ethical
as
possible? No, because an experiment, to be ethical, must be adequate
to test the hypothesis of interest. In particular, the sample size must
be
neither wastefully large nor so small that important findings are likely
to be missed. (“Chimps,
Ethics and Numbers: Appropriate Sample Sizes for Tests of Vaccines" from Laboratory Primate Newsletter,
Volume 28, No. 2, April 1989)
Primates are also used
in aging
studies.
Heart research, particularly
atherosclerotic disease is another area where primates are utilized.
With genetic similarity to humans of approximately 89%
and a relatively large size capable of providing ample fluid and tissue
samples, the baboon has served as an ideal experimental model for over
3 decades….
Known as the laboratory model for coronary heart and chronic lung diseases,
the baboon has also been used extensively in research involving atherosclerosis,
hypertension, and osteoporosis. (Bernacky, et. al., al.cit., p. 711)
Cynomolgus monkeys (crab
eating macaques or Macaca fasicularis) are the second most used species
of primates, after the Rhesus macaque; they are common in reproductive
biology studies as well as work with diseases such as cancer, atherosclerosis,
tuberculosis and viral illnesses.
Chimpanzees occupy a
unique place in scientific research due to their 98% genetic similarity
to human primates.
Chimpanzees are expensive and difficult to manage in a biomedical
setting….However, because of their phylogenetic similarities to humans, chimpanzees
have been attractive animal models for limited, sophisticated, nonconsuming
types of research. Their use in biomedical research has always evoked public
concern and continues to challenge our evolving ethical, legal and social
perspectives. Their significant contributions to biomedical research are
undeniable, as is our obligation to maintain these research veterans in a
high-quality life setting for their lifetime of 40-50 years…….The unique
ability of chimpanzees to resist or develop a milder form of some human diseases
like hepatitis, HIV, malaria, and Alzheimer’s, as well as the question of
why chimpanzees rarely develop cancer, has made the chimpanzee an attractive
comparative research subject. (Bernacky, et.al., al.cit.p. 715)
An 80 page report on xenotransplantation
research in the United Kingdom focuses on the many complex ethical
issues with this sort of work.
Primates in Biomedical
Research is an online database search via the Info Net from the Wisconsin
Primate Research Center.
Additional resources and data bases
A major resource is PrimateLit, a
bibliographic site sponsored by NIH and maintained by the Wisconsin Primate
Center. Their Veterinary Resources listing
has extensive online articles on a wide variety of husbandry and health
issues.
The Primate Information Network is a
web resource from the Wisconsin
Primate Research Center.
The Journal of Medical
Primatology has an online search site.
Another web resource, NetVet, contains
extensive links for Primates.
For those in the primate laboratory community,
see the Laboratory Primate Newsletter.
A clearinghouse for Training
in Primatology is maintained by the International Primatological
Society
The National Academies
Press has an online book, Occupational Health and Safety
in the Care and Use of Non-Human Primates.
The National Academies
Press has an online book, The Psychological
Well-Being of Non-Human Primates.
Study Questions:
1. The practice of euthanizing
research animals when they are no longer needed is common. This practice
has been questioned in the case of chimpanzees. After reading Appendix
A, A Minority Statement, from the NAP online book, Chimpanzees in
Research: Strategies for Their Ethical Care, Management and Use (1997)
would you support euthanasia or not for retired chimpanzees? Why or why
not?
2. Do you think the ethical
questions over using primates in research depend on the specific primate
species being used? Why or why not?