8—
Old World Monkeys: Cercopithecids

Scientific Name1

Common Name

CERCOPITHICIDAE (cercopithecids)

 

CERCOPITHECINAE (cercopithecines)

 

Macaca sp.

macaque

Macaca arctoides

stumptail macaque

Macaca assamensis

assam monkey, mountain monkey

Macaca cyclopsis

Formosan macaque

Macaca fascicularis

crabeaters, crab-eating macaque, cynomolgus (or cyno), irus monkey, Java monkey, kra (or kera), long-tail macaque, Philippine monkey

Macaca fuscata

Japanese macaque, snow monkey

Macaca mulatta

rhesus monkey

Macaca nemestrina

pigtail macaque

Macaca nigra

Celebes black ape, Sulawesi macaque, crested macaque, Cynopithecus niger

Macaca radiata

bonnet monkey

1  

This is a list of scientific and common names of species discussed in this chapter, not a comprehensive taxonomic list.



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--> 8— Old World Monkeys: Cercopithecids Scientific Name1 Common Name CERCOPITHICIDAE (cercopithecids)   CERCOPITHECINAE (cercopithecines)   Macaca sp. macaque Macaca arctoides stumptail macaque Macaca assamensis assam monkey, mountain monkey Macaca cyclopsis Formosan macaque Macaca fascicularis crabeaters, crab-eating macaque, cynomolgus (or cyno), irus monkey, Java monkey, kra (or kera), long-tail macaque, Philippine monkey Macaca fuscata Japanese macaque, snow monkey Macaca mulatta rhesus monkey Macaca nemestrina pigtail macaque Macaca nigra Celebes black ape, Sulawesi macaque, crested macaque, Cynopithecus niger Macaca radiata bonnet monkey 1   This is a list of scientific and common names of species discussed in this chapter, not a comprehensive taxonomic list.

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--> Macaca silensus lion-maned macaque, lion-tail macaque, wanderoo Macaca sinica toque monkey Macaca sylvanus Barbary ape Macaca thibetana Tibet monkey Papio sp. baboon Papio cynocephalus anubis olive baboon Papio cynocephalus cynocephalus yellow baboon Papio cynocephalus papio West African baboon, Guinea baboon Papio cynocephalus ursinus chacma baboon Papio hamadryas hamadryas baboon, sacred baboon Mandrillus sp. drill, mandrill Theropithecus sp. gelada Cercocebus sp. mangabey Cercocebus torquatus atys sooty mangabey Cercopithecus sp. guenon Cercopithecus aethiops African green monkey, grivet, vervet Miopithecus sp. talapoin Erythrocebus sp. patas monkey, military monkey, hussar monkey, mustached monkey Allenopithecus sp. Allen's swamp monkey COLOBINAE (colobines)   Colobus sp.   Colobus abyssinicus black and white colobus monkey Colobus badius red colobus Presbytis sp. langur Presbytis entellus hanuman langur, sacred langur Rhinopithecus sp. snub-nosed langur Rhinopithecus roxellana Chinese golden monkey Nasalis sp. proboscis monkey Nasalis larvatus proboscis monkey Simias sp. Mentawi island langur Pygathrix sp. douc langur The Old World monkeys (cercopithecids) are divided into two subfamilies, the cercopithecines (which have check pouches) and the colobines (leaf-eating monkeys) (Napier and Napier 1967, 1985). The cercopithecines are represented in Asia and North Africa by one genus (Macaca); the rest are found only in sub-Saharan Africa, except Papio hamadr-

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--> yas (the sacred baboon), which is also found on the Arabian peninsula. Macaca (macaques) and Papio (baboons) are generally considered closely related, and Papio is also closely related to Theropithecus (geladas) and Mandrillus (drills and mandrills). Cercocebus (mangabeys) is considered intermediate between these genera (Macaca and Papio) and other cercopithecines, and some would divide the mangabeys into two genera according to the degree of similarity to Macaca and Papio or to Cercopithecus (guenons). The guenons include many of the colorful forest species and the vervet or green monkey (Cercopithecus aethiops ). Miopithecus (talapoins) and Erythrocebus (patas monkeys) are closely related. Allenopithecus (Allen's swamp monkey) is poorly known. The colobines are found in both Africa and Asia; greater diversity occurs in Asia. African forms are sometimes placed in the single genus Colobus, but some authorities prefer to recognize several distinct genera. All agree that Asia has multiple genera of colobines, including Rhinopithecus (snub-nosed langurs—one species is known as the Chinese golden monkey) and Nasalis (proboscis monkey). Pygathrix (douc langurs) and Simias (Mentawi island langurs) are also generally recognized; the remaining langurs are either all grouped as Presbytis or divided into several related genera. Old World monkeys all develop ischial callosities (specialized calluses used in sitting) prenatally and have the same dental formula as apes and humans: two incisors, a canine, two premolars or bicuspids, and three molars in each quadrant. Sexual size dimorphism is pronounced in many of the larger species. Other morphological characteristics—such as tail length, the presence of female sexual swellings, and distinct natal coat colors in infants—are extremely variable. Old World monkeys include many forms that spend substantial portions of the day on the ground. Geladas and some baboons can live in areas where there are few trees, and they retire to rocky cliffs at night. Patas monkeys are also highly adapted to life on the ground. Most other forms, however, are never far from trees. Even macaques, which some describe as semiterrestrial, spend most of the day in elevated locations and seek the refuge of trees at night. The colobines have enlarged salivary glands and a sacculated stomach and can digest mature leaves. They nevertheless prefer a diet of fruit, flowers, seeds, and buds and consume both young and mature leaves (Napier and Napier 1985; Struhsaker 1975). Cercopithecines are much more omnivorous, and some macaques will eat virtually anything that humans find edible, in addition to many items that humans pass by. This flexibility means that some macaques and baboons live close to humans in the wild state and will raid crops, steal from markets, and seek handouts from humans. The most commonly seen monkey in captivity is Macaca mulatta (rhesus monkey), sometimes called the Indian monkey, although its distribution extends from Pakistan through India, Bangladesh, Burma, and Thailand into northern China (Napier and Napier 1985). Until recently, this was the laboratory monkey.

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--> Substantial breeding colonies exist in the United States to supply the needs of federally mandated testing programs (Erwin and others 1995). More recently, Macaca fascicularis has gained popularity in many laboratory programs. Limited numbers are available from the wild, but concerted efforts are under way in source countries to breed them. Rhesus monkeys can no longer be imported from India to the United States under Indian law, and relatively few are available from other countries (Johnsen 1995). The smaller long-tail macaques have a variety of common names, including long-tail macaque, cynomolgus (or cyno), crabeater, Java monkey, Philippine monkey, kra or kera, and irus monkey. They are found in southeast Asia and in the islands of the Philippines and Indonesia and exist as feral populations on a number of other islands where they have been introduced (e.g., Mauritius). Other macaques often seen in captivity include M. nemestrina (pigtail macaques), M. arctoides (stumptail macaques, referred to as M. speciosa in older publications), M. fuscata (Japanese macaques or snow monkeys), M. sylvanus (Barbary apes), and, less commonly, M. assamensis (assam or mountain monkeys), M. radiata (bonnet monkeys), M. sinica (toque monkeys), M. cyclopsis (Formosan macaques), and the Sulawesi forms, which may be divided into up to seven species and include Celebes black apes, moor, tonkean, and Hecht's macaques. The older literature lists the Celebes black ape as Cynopithecus niger, but all the Celebes, or Sulawesi, forms are now accepted as macaques. The remaining macaques include Macaca silensus (the wanderoos or lion-tail or lion-maned macaques) seen in a few exhibition and breeding colonies, and M. thibetana (the Tibet monkeys), seen only in a few exhibits outside China. The inappropriate use of the term ape in many common names reflects the presence of a very small tail sometimes overlooked by early explorers who called any monkey without a tail an ape. Baboons of one type or another are also often seen in captivity. These are large, sexually dimorphic monkeys. The males often display canine teeth that rival those of lions and tigers in length, and a large male can weigh as much as 40 kg (88 lb). Baboons are found from West Africa across East Africa and south to the Cape of Good Hope. Most recognize Papio hamadryas (the sacred baboon) as a distinct species but argue about how to distinguish taxonomic groups represented by West African or Guinea, yellow, olive, and chacma baboons among the savanna forms. P. cynocephalus is used as the inclusive name; others are listed either as subspecies or species separate from the yellow baboon. The gelada (Theropithecus gelada) and the colorful mandrill (Mandrillus sphinx) and less common drill (M. leucophaeus) are sometimes also referred to as baboons because they are also large African monkeys. They are sometimes popular in exhibits but much less common than the true baboons. Mandrill males have been weighed at over 50 kg (110 lb) and are very powerful animals. A similar situation to the savanna baboon exists for another common form of African monkey in captivity, Cercopithecus aethiops. The West African forms are the largest and have the greatest sexual dimorphism. They do not have the

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--> red, white, and blue hindquarter display of East African forms and are sometimes called green monkeys instead of vervets. Differences in facial hair patterns distinguish grivets as well, but common names are not used consistently, and most lump all into a single species. The West African forms are likely ancestral to the wild populations found in several islands in the West Indies, but individuals from the West Indian population are smaller than those in the West African populations. Patas, talapoins, and mangabeys are also found in captivity with some frequency, and patas are also called hussar, military, or mustached monkeys by some exhibitors. Other guenons are often seen in exhibits but seldom in laboratories. Colobines are less often seen in captivity, and this can be attributed primarily to problems in developing adequate diets. The spectacular black and white colobus monkey (Colobus abyssinicus) and the sacred or hanuman langur (Presybytis entellus) are most often seen in exhibits. Representatives of other colobine genera from Asia are less often displayed, but many Americans have seen the Chinese golden monkey (Rhinopithecus roxellana) and have seen postcard pictures of the proboscis monkeys (Nasalis larvatus) maintained in captivity. A variety of social organizations characterize the Old World monkeys, but all are intensely social, spending all their lives in social groups except for brief periods of transfer between groups (Dittus 1980). In most cases, it is the male that transfer; but even in species in which males might spend some time out of a breeding group, they can form all-male bands and continue to live in a social milieu; in some species, a male can spend time as a solitary animal when in transit between sexual groups. Housing Old World monkeys have been successfully maintained in a variety of housing conditions in captivity. Types of housing include individual cages in climate-controlled buildings, indoor mesh pens, indoor-outdoor runs, corn cribs, corrals, and semi-free-ranging conditions, such as islands. If properly acclimated and afforded protection from wind, sun, and rain, some species can live outdoors in temperatures from around freezing to over 39°C (102°F) and in relative humidities characteristic of desert or tropical environments. When maintained in climate-controlled environments, these monkeys do well under conditions comfortable for humans (NRC 1996). The design of housing for Old World monkeys differs little from that described in Chapters 2 and 3. Most housing was indeed developed in maintaining Old World monkeys. These are generally robust primates that will shake and attack cage structures, and sturdy construction is in order. Although many spend considerable periods on the ground, virtually all flee upward when disturbed, and they will use the upper portions of a cage preferentially if given perches or suitable structures to

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--> allow for use of the full volume of a cage (Watson 1991). Species differ in the extent of manipulative curiosity, but all should be considered as potentially destructive. This should be taken into account in the design of cages, swings, puzzles, toys, and other enrichment devices. Cage height should consider the length of the animal's tail so that it will not touch the floor when the animal is sitting on a perch (NRC 1996). Cage furnishings should be routinely inspected for broken and hazardous items that need to be repaired or replaced. Some of the first demonstrations of visual curiosity in nonhuman primates were carried out in Old World monkeys (Butler 1954). Most enrichment devices described in Chapter 2 were designed with Old World monkeys in mind and serve well for enriching singly-housed rhesus monkeys (see also Line and others 1990a). Nutrition The dietary requirements for cercopithecine monkeys have been defined sufficiently to allow for successful breeding, growth and development, and maintenance (NRC 1978, 1996). If nutritional problems occur, they usually result from mismanagement of the diet, such as in its manufacture or storage. Appropriate handling of feed is described in the Guide for the Care and Use of Laboratory Animals (NRC 1996). Cercopithecines can be successfully maintained solely on a fresh commercial feed, even though this is not recommended. Offering a variety of foods contributes to their psychological well-being (see discussion in Chapter 3). They will eat a wide variety of fruits, vegetables, and grains. Peanuts, popcorn, unsalted pretzels, dry cereal, shelled dry corn, millet seeds, and sunflower seeds can be used as treats; but potential contamination of natural food items should be considered, and reasonable caution is in order. Whereas adequate diets of wholesome foods obtained from the market can be achieved, it is far more convenient to ensure nutritional balance by using one of the many specially formulated commercial diets. Commercially available, nutritionally balanced food treats come in a variety of sizes, shapes, colors, flavors, and textures. The colobines are more difficult to provide for nutritionally. Their diet should be heavily supplemented with green leafy vegetables. Some institutions have found that alfalfa is of benefit in caring for some colobines. A good commercially available diet is best to start with, but it will require considerable supplementation to maintain colobine monkeys. Social Behavior Most species of macaques and baboons live in large troops consisting of numerous adults of both sexes. These social groups are often divided into smaller units called matrilines, which consist of mothers and their female offspring. Adult males are immigrants, unrelated to the females, that leave their natal troop

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--> at around the time of puberty (Dittus 1980). In contrast, females spend their entire lives in their natal troop. The sex ratio of adults is typically female-biased. This has been attributed in part to the mortality associated with adolescent male emigration and in part to the longer developmental periods of males. Most social groups usually move through their habitat as a single large troop, but some flexibility in forming subgroups can be seen. Whereas that general pattern applies to most macaques and baboons, some exceptions should be noted. Hamadryas baboon troops are divided into one-male units (an adult male with several adult females and their offspring). Males actively ''herd" their females, but males of several of these units will act together to repel predators or intruders. Furthermore, a large loose troop structure can be discerned during the evening, when several bands are found in proximity on cliff faces. Geladas also form one-male units, but males do not herd females. Unlike hamadryas baboons, in which one-male units disperse during the day, gelada units disperse at night and can form large feeding herds on days when feeding conditions are favorable. The social organization of the mandrill and drill are less well known, but basic one-male units have been suggested for these forest-floor dwellers. Guenons, with the exception of vervets, and patas monkeys generally live in small one-male units. During the breeding season, males might temporarily enter some breeding groups, but, in patas monkeys at least, other males are generally found in all-male bands. Talapoins typically live in large social groups consisting of many adults of both sexes. In captivity, females might dominate males when not in breeding condition, and new males might be attacked by females. The presence of strong matrilines is characteristic of groups of macaques and baboons in expanding populations, but strong matrilineal subgroups might not be universal. They are not readily detected in declining populations or in those in equilibrium, and evidence of strong matrilineal organization is not found even in expanding troops of sooty mangabeys (Cercocebus torquatus atys). The social organization of the various mangabey species is not yet well described. Colobine monkeys generally live in one-male units with other males living in all-male bands. Colobus badius (red colobuses) and Rhinopithecus (snub-nosed langurs) form multimale troops of somewhat larger size. Some variation is also noted among Presbytis entellus (hanuman or sacred langur), in which multimale troops might exist temporarily or more permanently in some habitats. Many African monkeys form polyspecific associations in the wild, and mixed-species groups of guenons have been maintained in captivity without adverse consequences. The high prevalence of simian AIDS viruses in African monkeys, however, argues against mixing them with Asian species. Macaques in particular appear to be highly susceptible to such infections. Different species of macaques will also readily hybridize when mixed-species pairs are formed; however, even though compatible pairs tolerate each other, macaques generally do

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--> not do well in mixed-species groups, and formation of such groups for social enrichment is not recommended. Reproduction and Development Old World monkeys exhibit true menstrual cycles with the sloughing of the uterine wall lining at the end of the luteal phase of the cycle if fertilization has not taken place (Catchpole and Van Wagenen 1975). Some species (e.g., rhesus, bonnet, and Japanese macaques) are seasonally polyestrous with a hiatus in ovulatory cycles during late spring and summer months. Others (e.g., crab-eating macaques) show seasonality only in some circumstances. Other Old World monkeys might show a tendency to give birth more frequently in some months (e.g., sooty mangabeys), whereas others seem to give birth with equal frequency in all months. Indoor housing can be expected to alter these observations from wild populations. Menstrual cycles are generally 4–5 weeks long, and copulations tend to be concentrated at midcycle, although some species (e.g., Macaca arctoides) seem less hormonally controlled and others respond more to social conditions than to absolute hormone concentrations (e.g., rhesus monkeys). Sexual swellings (edematous engorgement of the skin, usually in the perineal area) are distributed in an erratic pattern among Old World monkey taxa. In species in which they do occur, females will cycle between full swellings at or near the time of ovulation to no swelling during the late luteal early follicular phase. Some taxa also maintain partial or even large swellings during pregnancy. Sexual swellings and other visual, chemical, auditory, and behavioral cues might synchronize the reproductive activity of the two sexes. The size of sexual swelling varies among species and among individuals within a species. In some taxa, it is common only among adolescent females and disappears in fully mature females. In some species, clear evidence of male–male competition is seen (e.g., baboons), but female choice also plays an important role (e.g., in rhesus monkeys). In some, consortships are formed that endure beyond the time required for copulation; but in most multimale groups, females will mate with more than one male, and the degree of correlation between dominance, observed matings, and paternity is highly variable. Male–male competition is highly variable in expression, but in most groups male aggression is ritualized and produces few serious injuries. Under natural conditions, male transfer between groups during the breeding season might account for more wounding than males fighting over females (Ruehlmann and others 1988). Infanticide has been reported in several locations for hanuman langur when a new male takes over a group (Blaffer Hrdy 1977). Although suggested in a wide variety of other species, its prevalence is debatable. In most cases, even when it does occur, it is most likely when a new breeding male replaces the former resident male.

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--> Gestation generally requires 5-6 months, and a single infant is usually produced. Infants sometimes are dramatically different in coat color from adults and often have unpigmented hands and faces. That condition does not vary according to any systematic taxonomic scheme, and the period before full adult coloration varies. The functional significance of natal coats remains speculative. Weaning is not an abrupt event but a process lasting over several months. Although many infants continue to nurse until the next sibling is born, most can feed themselves at 6 months but remain socially dependent on their mothers and return to their mothers when disturbed and to sleep. Young infants are carried ventrally, and only in some species (e.g., baboons and geladas) do they predictably transfer to dorsal carriage after the first 2 or 3 months (Altmann 1980; De Vore 1963). After the first year, juvenile animals can become more and more involved in peer groups, especially males. Several years might pass before puberty occurs. Puberty is also not an event but a process, and the gradual change to full adult status can take several years, a period sometimes recognized as the period of adolescence and subadult states (Bernstein and others 1991). First menstruation can precede fertility by a year or more and often occurs when a female is only half her full adult weight and before she sheds all her milk dentition (deciduous teeth). Males can achieve fertility long before they normally participate as adult males in breeding. It is during this time that males often transfer out of their natal group. Cercopithecine monkeys are relatively easy to breed in captivity, and infants can be produced under almost any condition that allows a fertile male access to an ovulating female. Early rearing conditions, as discussed in Chapter 3, will have a substantial impact on the social development of infants and later reproductive competence. In general, infants reared in social contexts that approximate those of natural troops have the best prognosis as future breeders. Cognition Studies of cognition using Old World monkeys have generally focused on macaque subjects. Rhesus monkeys have been the subject of numerous perceptual studies, and information on visual capacities is summarized in De Valois and Jacobs (1971). (See also Bayne and Davis 1983 and Leary and others 1985.) Whereas Old World monkeys are not generally recognized as tool-users, they are highly skilled in manipulating objects. They are adept at numerous puzzle problems (e.g., bent wire) and readily learn to use joysticks to perform video tasks (Washburn and Rumbaugh 1992). Once skilled in a task, they will work at it with persistence, not needing to be rewarded with food to sustain their performance (Harlow and others 1950; Washburn and Rumbaugh 1992), but they prefer to work on tasks of their own selection. Many activities originally reinforced with food seem to become reinforcing in themselves, and monkeys will often work a familiar task, ignoring the food rewards offered.

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--> Although capable of complex learning, monkeys have not displayed the kind of language skills seen in the great apes (Savage-Rumbaugh and others 1998). Gallup (1982) suggests that there is a large cognitive discontinuity between the great apes and monkeys as demonstrated by their consistent failure in such tasks as recognizing themselves in mirrors. The significance of mirror self-recognition in studies of cognitive capacity is controversial, and self-awareness might not be dependent on self-recognition in a mirror; moreover, not even all great apes demonstrate such a capacity. Great apes do, however, appear to show a greater diversity of learning skills than any monkey taxon, although most great apes' accomplishments might be matched in some particular monkey taxon. The common practice of housing rhesus monkeys singly calls for special attention because it is well established that social deprivation can be counter to the goals of this report (Bayne and Novak 1998). Although many of these animals might become pair-housed as encouraged in this document, others will remain singly housed for reasons of research, incompatibility, or health. Addressing the welfare of these singly housed animals requires a concerted approach by investigators, veterinarians, and IACUCs. Every effort should be made to house these animals socially (in groups or pairs), but when this is not possible, the need for single housing should be documented by investigators and approved by the IACUC. A common approach is for the institution's environmental enrichment (or psychological well-being) plan to require all primates to be socially housed and to require justified exemptions for all others. There are reasons for single housing, that should not be accepted as the default situation. Institutions should provide social housing unless single housing is approved by the IACUC. Personnel It is essential that personnel working with Old World monkeys be made aware of the various disease risks involved (Adams and others 1995) and the fact that many Old World monkeys are capable of inflicting serious bite wounds and have surprising strength for their body size. Macaques and some other cercopithecines also interpret the human stare as a challenge and might attack a person who is visually inspecting them, but most monkeys are not constantly hostile to people and will respond to considerate and consistent treatment. Personnel must take reasonable precautions to protect themselves from disease risks and attack (CDC 1990, 1993; CDC-NIH 1993; NRC 1996, 1997a). Even members of species that are more tolerant of humans can suddenly attack humans if an infant screams or if there is some other sudden disturbance. Rhesus monkeys are consistently more hostile than other macaques toward people, but personnel working with even the tamest of monkeys should be alert to the potential for attack. Old World monkeys have been implicated in the transmission of several diseases to humans. (Adams and others 1995; CDC 1993; NRC 1997a). Most

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--> people prefer not to handle alert adults macaques and baboons, but human handling clearly is necessary to ensure the health and well-being of nursery-reared infant macaques and baboons. In the case of adults, techniques involving training, tunnels, pole and collar devices, leashes, transfer cages, and pharmacological restraint agents can greatly reduce the need for physical contact between monkey and human (Chambers and others 1992; Clarke and others 1988; Knowles and others 1995; Laude and others 1996; Phillippi-Falkenstein and Clarke 1992; Reinhardt 1992a, 1995, 1997a). Behavioral training is absolutely essential for caregivers and other relevant personnel (Laule and others 1996). Both baboons and macaques are hardy animals and stoic in response to illness and injury. The same is generally true of other cercopithecines and colobines. Moreover, the thick hair of many guenons might completely hide even extensive wounding. Good detecting skills might be required to discern wounds, emaciation, and other serious conditions. In general, only a knowledgeable and alert observer can recognize changes in individual behavior in a macaque or baboon that are indicative of altered health. Caregivers familiar with their charges can develop different strategies that facilitate the caregiver-monkey interaction with "difficult" animals. Most monkeys respond appropriately to consistent considerate treatment but can be quite dangerous when teased, tricked, or bullied. Veterinary Care No requirements for the veterinary care of Old World monkeys differ from the general requirements for nonhuman primates (Butler and others 1995; NRC 1996). Old World monkeys can be trained to cooperate in some routine procedures when those procedures occur regularly (e.g., the use of vaginal swabs and blood-sampling). In some cases, individual animals can even be trained to accept restraint for short-term treatment regimens, which eliminates the need to subject them to repeated pharmacological restraint. (See "Restraint and Training," Chapter 3.) Monkeys can be medicated for illness or for other reasons in several ways—through gavage or injections or by masking the agent in a food treat. Medications can be sprinkled or spread on bread and covered with peanut butter, jelly, or both; and they can be hidden in fruit. Monkeys will often suck on a tube for medicated fruit juice as well. Although oral dosing is least disruptive to the animal and thus most desirable, some monkeys will not eat the treat and so require other strategies. It is also important to determine that the monkey consumes the treat, rather than storing it in a cheek pouch and later rejecting it. Offering a second piece of food immediately often forestalls detailed inspections of the first treat by the animal. Knowledgeable personnel can determine which method works best and which foods mask medications best for a particular monkey. If any Old World monkey goes off-feed during an illness, it should be offered a variety of foods to stimulate appetite. For macaques, relatively bland but

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--> acceptable foods include cooked white rice, fruit-flavored yogurt, and bran cereal. Baboons are particularly fond of yams, fruit-flavored yogurt, and commercially prepared infant formulas. Ill monkeys are sometimes removed from their social group. As the time away from the group increases, the potential for successful reintroduction to the original group decreases. For very short stays (less than a couple of days), reintroductions are generally not traumatic, provided that aggression was not the initial reason for removal. Careful reintroduction and monitoring of the group for outbreaks of aggression will help safeguard animal well-being. If the animal is out for a long period, reintroduction to the original group might be contraindicated. In some cases, an animal removed for treatment can be housed in a cage within the group pen. That permits access for treatment but at the same time maintains social contacts. Difficulties during reintroduction vary according to species. They are most common in macaques, such as rhesus and crab-eating monkeys, and less in other species, such as baboons. A number of diseases are transmissible from monkeys to humans and vice versa (Adams and others 1995; CDC 1993; CDC-NIH 1993; NRC 1997a). The most publicized risks involve cercopithecine herpesvirus 1 (Herpesvirus simiae or B virus), which is known to be carried by a high percentage of macaques and may be carried by other Old World monkeys—which produces little outward sign of infection in macaques but is almost always fatal in humans. During the active phase, the virus can be transmitted to humans through bites or scratches. It can also be transmitted to human mucus membranes (e.g., in the eyes) from discharges from various bodily orifices of macaques or other inanimate objects or materials on which disease–producing agents can be conveyed (fomites). The number of recorded human infections is small, considering the number of people working with Old World monkeys, but prudence is certainly in order in the handling of Old World monkeys. Ebola-Reston virus, another disease of Old World monkeys is not known to have caused any morbility in laboratory animal workers (although serum titer conversions have been documented), but the consequences of exposure are severe and prudent precautions must be observed (Adams and others 1995; CDC 1990; CDC-NIH 1993; NRC 1997a). Unlike the macaque, the baboon has no specific disease entity that is considered zoonotic. In both macaques and baboons, bacteria—such as shigellae, salmonellae, staphylococci, and E. coli—are sometimes found and are transmissible to humans. Of particular significance for Old World monkeys is tuberculosis, which can be transmitted from humans and by other infected monkeys. Although tuberculosis in primates is not reportable to the Centers for Disease Control and Prevention (CDC), except during quarantine (CDC 1993), the most frequently used species (rhesus monkeys and crab-eating macaques) have had the most reports of infections. Tuberculosis is also a possible but less–probable infection in baboons. Primates and all personnel working closely with them should be routinely screened for tuberculosis.

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--> Seizures, similar to human epileptic seizures, are sometimes seen in macaques, baboons, and chimpanzees. Medications used for epileptic humans sometimes are effective in alleviating the problem in macaques and baboons. Although many seizures can be traced to traumatic origins, some are thought to be genetically influenced, and this should be considered in breeding programs. Animals subject to seizures should be maintained in cages that decrease the risk of injury during seizures (e.g., by avoiding the possibility of long falls to a hard floor). Readers should refer to Bennett and others (1995) and Occupational Health and Safety in Research Animal Facilities (NRC 1997b) for a comprehensive discussion of the diseases of nonhuman primates. All primates imported into the United States must undergo a minimal 31-day quarantine period at a CDC-licensed and CDC-inspected facility (CDC 1991, 1993). This rule includes wild-caught animals and those from captive breeding colonies. As a result of a suspected filovirus threat associated with newly imported animals in 1989 (CDC 1990), the CDC quarantine requirements became much more rigorous. Special permits and transportation restrictions were developed for three species (rhesus monkeys, crabeaters, and African greens or vervets). The special transportation and quarantine requirements have now been extended to cover all primates. The protective clothing, limited access of personnel, restriction of human interaction, disinfection requirements for equipment or objects being taken out of the quarantine areas, and relatively short holding times make many environmental enrichment and well-being programs used in normal colony situations difficult to accomplish during CDC quarantine. Nonetheless, many of the enrichment options discussed in Chapter 3 can be provided: some animals can be socially housed, caging can be arranged so that animals can see and hear each other, food treats and supplements that do not require special delivery devices can be offered, perches can be provided, and uniform procedures can be established early so that animals can anticipate regular husbandry events as soon as possible. During quarantine, well-trained and motivated caregivers can provide an enormous difference in reducing the stress of the animals. Despite the limitations imposed by quarantine, a variety of enrichment techniques are possible and will prove especially beneficial under the restrictive conditions of quarantine.