Scientific Name1

Common Name



LEMURIIDAE (lemurids)


Lemur catta

ring-tailed lemur

Eulemur fulvus

brown lemur

Eulemur mongoz

mongoose lemur

Eulemur rubriventer

red-bellied lemur

Varecia variegatus

ruffed lemur

Hapelemur sp.

gentle lemur

CHEIROGALEIDAE (cheirogaleids)


Cheriogaleus medius

fat-tailed dwarf lemur

Microcebus murinus

lesser mouse lemur

Mirza coquereli

Coquerel's mouse lemur

INDRIDAE (indrids)


Indri sp.


Propithecus sp.




Daubentonia madagascariensis



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

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--> 5— Prosimians Scientific Name1 Common Name Lemurs   LEMURIIDAE (lemurids)   Lemur catta ring-tailed lemur Eulemur fulvus brown lemur Eulemur mongoz mongoose lemur Eulemur rubriventer red-bellied lemur Varecia variegatus ruffed lemur Hapelemur sp. gentle lemur CHEIROGALEIDAE (cheirogaleids)   Cheriogaleus medius fat-tailed dwarf lemur Microcebus murinus lesser mouse lemur Mirza coquereli Coquerel's mouse lemur INDRIDAE (indrids)   Indri sp. indri Propithecus sp. sifaka DAUBENTONIIDAE   Daubentonia madagascariensis aye-aye 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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--> Lorises and galagos   LORISIDAE (lorisids)   Galago crassicaudatus thick-tailed galago Galago senegalensis dwarf galago, senegal galago LORISINAE (Lorisines)   Loris tardigradus slender loris Nycticebus coucang slow loris Tarsiers   TARSIIDAE (tarsiids)   Tarsius sp. tarsier This chapter is a brief summary of extensive published data. For more information and additional data on lemurs and other prosimians, consult Harcourt and others (1998); IUCN (1990); Segal (1989); Bennett and others (1995); and UFAW (1987). The suborder Prosimii might constitute the most diversified set of living mammals. One major group, collectively referred to as lemurs, occurs in nature only in the Malagasy Islands. Its major taxonomic subgroups are the true lemurs (Lemuriidae), mouse and dwarf lemurs (Cheirogaleidae), indris and sifakas (Indridae), and perhaps the phylogenetically oddest of all primates, the aye-aye (Daubentonidae). Few are maintained in captivity; the most likely representatives to be seen in captivity are the Lemuriidae: the ring-tailed lemur (Lemur catta), the brown lemur (Eulemur fulvus), and the ruffed lemur (Varecia variegatus). A second major group (Lorisidae) consists of lorises and galagos. All galagos in nature are from Africa; two members of the loris group are from Africa and two from Asia. Galagos are sometimes referred to as bushbabies, but this common name is sometimes applied to other animals as well. The thick-tailed galago (Galago crassicaudatus) and dwarf galago (G. senegalensis) are the only members of this group seen more than rarely in captivity. A third major group consists of the tarsiers (Tarsius), from the islands of southeast Asia. The taxonomic position of tarsiers remains controversial; these animals are difficult to maintain in captivity, and few institutions attempt to do so. Prosimii vary widely in size, dietary preferences, locomotor adaptations, social organization, and intelligence. Living prosimians range in size from the mouse lemur, with a body length of about 12 cm (5 in) and a weight less than 100 g (4 oz), to the tailless indri, with a body length of about 90 cm (3 ft). Different dietary adaptations in various genera and species are reflected in major differences in the alimentary tract. Differences in locomotor styles are reflected in major anatomical differences. All those contribute to the observed diversity in behavior and social organization. As body size and locomotor habits vary widely,

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--> so do requirements for housing and living space. There are agile leapers and slow climbers, predominantly arboreal and mainly terrestrial prosimians. There are insectivores, highly specialized leaf-eaters, bamboo-eaters, fruit-eaters, and omnivores. Some species occupy tree holes or build nests that are used as general sleeping quarters or primarily for the care of infants. Some prosimians give birth to twins or small litters, whereas the norm for most species is a single offspring. Some prosimians resemble bats in having ultrasonic calls, and some species have very complex vocal repertoires. A few species even exhibit periods of torpor resembling hibernation. Almost every prosimian species has its own distinctive life style. Some live in large groups, others in small groups; some travel alone, some in pairs. Most prosimians scent-mark and urine-mark their surroundings, others also mark with feces. There might be a greater diversity of scent glands on various body parts in prosimians than in any other mammal, and the ability to maintain scent marks in their environment appears to be important for the general well-being of prosimians. Despite the enormous diversity of prosimians, a few general comparisons between prosimians and other primates can be made. Prosimians are less inquisitive, less restive, and less destructive to their environment than other primates; the only exception is the aye-aye, which will gnaw through structures. Prosimians are the primates farthest removed from humans, and there is much less likelihood of disease transmission between humans and prosimians than between humans and other primates. In fact, no case of a transmission of a zoonosis from prosimian to human could be found in a search of the literature. In contrast with other primates, which (with the single exception of the night monkey, Aotus) are diurnal, prosimians are primarily nocturnal. Only among the lemurs are there some diurnal forms. Some are also crepuscular (active only at dawn and dusk), a few are cathemeral (being sporadically active throughout the 24-hour cycle), and a few display some flexibility in circadian rhythms. The captive maintenance of prosimians must take these patterns into account. Some institutions might wish to maintain reverse light cycles by using regular room lighting at night and low levels of red illumination during the day so that caregivers can observe them during their active period. The Duke University Primate Center has had the most comprehensive experience in the care of prosimians of any institution in the United States and is the largest captive prosimian colony in the world (Bennett and others 1995). The committee's recommendations are based largely on successful experiences at Duke. Housing Prosimians can be kept safely in a wide variety of cages and enclosures, ranging from multihectare outdoor habitat enclosures, corrals, and large indoor

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--> rooms to complexes of small wire cages or even small single cages with a volume of 1 or 2 m3. For monitoring and protection from hypothermia, the smaller, mainly nocturnal forms are best kept indoors on reversed lighting schedules. Prosimians rarely attack cage structures. Perhaps as a consequence of their ability to leap and move rapidly through thorny scrub in their natural habitat, they are less likely than other primates to be injured by wire. Wire cages provide extensive climbing surfaces for small prosimians. Prosimians make good use of shelves, ropes, or swings and do well with natural substrates—such as vines, bamboo, and branches—to climb on or jump among. With regular cleaning and replacement of cage furniture, wooden objects have not been implicated as natural-disease vectors. Attempts to keep and breed promising under conditions that maximized sanitation and lacked nest boxes or appropriate substrates for climbing and jumping affected reproduction and survival adversely. In fact, the effects of long-term housing under these conditions were not readily reversed when the animals were provided more suitable housing in which other members of their species thrived. True lemurs (Lemur, Eulemur, and Varecia) do well in large outdoor enclosures. Some success has been reported in smaller runs with a minimum of 5 m3 (175 ft3) per animal. Indoor rooms may also be used, although lights must be kept on a timer or on a manual light cycle designed to simulate seasonal photoperiod changes to ensure breeding. Concrete flooring of either indoor or outdoor enclosures is contraindicated because animals have been killed by falls onto concrete surfaces. Heated shelters larger than 60 cm square (2 ft square) should be provided with resting and feeding shelves. Under severe weather conditions, lemurs might need to be secured in sheltered housing because some will not use heated shelters regularly otherwise. Lemur housing should be furnished with vertical and horizontal natural substrates, such as vines, bamboo, and branches. Weekly sanitation of PVC "branches" has been associated with anogenital micro-abscesses in Varecia. Natural substrates sanitized less frequently do not produce such problems. Large forested enclosures are suitable for lemurids, and one enclosure can hold species of all lemurid genera, inasmuch as these species are not hostile or competitive toward each other. The use of electric fencing is effective when groups are socially stable, but animals rejected by their social group will escape over such fences. Sand or grass flooring in enclosures can be maintained if spot-cleaned and raked daily. The Duke Primate Center has found weekly sanitation of shelter-box interiors and monthly sanitation of the cage furniture, nest boxes, and windows to be effective in maintaining sanitation and providing essential species odors. In contrast with true lemurs, Cheirogaleidae (mouse and dwarf lemurs) seldom jump more than a meter and are conveniently housed in cages containing family groups of pairs or trios of animals plus the season's juveniles. Cages as small as a 1.2-m cube (3.9-ft cube) appear to provide adequate space for such

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--> groups.2 Cages constructed of coated wire are very light and can be hung from the walls in easily sanitized rooms. On the basis of the experience of the Duke center, we recommend that the cages themselves be sanitized no more than once a month—and less often when infants are present. Cage-washing seems to be stressful to these animals, and there are no reports of infectious-disease problems or spread of disease among captive mouse and dwarf lemurs housed in cages cleaned even less frequently. To protect against falls when they are kept in indoor rooms, floors can be coated with about 5 cm (2 in) of sand or wood chips, which should be spot cleaned daily. "Nest boxes" composed of plastic tubing of various diameters to accommodate larger and smaller cheirogaleids are recommended. The Indridae (indris and sifakas) have highly developed leaping abilities—individual jumps can be up to 7 m (23 ft) laterally—and they need more space and more vertical supports than do other prosimians. Small families have been successfully maintained in indoor rooms of 5 x 7 x 6 m (16.4 x 23 x 19.7 ft). In warmer climates, these animals can be released into large outdoor enclosures, but they will need access to heated shelter boxes during colder weather. Indrids stop feeding and enter such warm quarters long before sunset. Heat lamps should be in more than one location because males are sometimes excluded from choice sleeping sites. Aye-ayes (Daubentoniidae) will gnaw cage structures with their large chisel-like front incisors and require sturdier housing than other prosimians. They are adept at climbing and leaping and have been bred successfully in an indoor room of 5 x 5 x 5 m (16.4 x 16.4 x 16.4 ft) with extensive vertical and horizontal branches as well as ropes and vines for climbing and swinging. They require a nest box for short periods of rest and daytime sleeping. Aye-ayes stuff their nest boxes with branches, leaves, or straw as available. They normally live independently in the wild, but when provided with two or more nest boxes, mixed-sex pairs can live together after a period of adjustment. Floors should be covered with wood chips to prevent injury from falls and to absorb the normally dry fecal material and urine. Daily spot cleaning and monthly replacement of chips have proven sufficient. Lorises and galagos tolerate few others in small cages. Large cages and cages partitioned into several chambers connected by wire tunnels that can variously be closed off can be used for breeding. Males should be separated from newborn infants with double-wired partitions because they sometimes attack 2   Although the use of this size cage represents an exception to the size recommended in the Guide and required by the Animal Welfare Regulations, it has been found satisfactory for very small prosimians and approved for such use by the USDA at the Duke Primate Center. Other facilities are encouraged to seek similar approval if using caging not in compliance with the regulations.

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--> infants. A nest box is required by all. The slow-moving lorises, as opposed to the more active galagos, require multiple horizontal branches and platforms for resting and marking. Because lorisines have a "dropping response" when startled (i.e., they fall to the floor), floors should be well cushioned with shavings or other suitable material. Tarsiers are active jumpers, and a male and female will need an enclosure about 2 x 2 m (6.6 x 6.6 ft) and 3 m (9.8 ft) high to allow for leaping. In larger enclosures, they can be kept in groups. Rooms or cages should be furnished with multiple vertical bamboo poles, tree branches, and vines. Tarsiers will not use a nest box but do like to sit in tangles of vines. The substrate of cage furniture needs to provide ample climbing surfaces so that insects and lizards, introduced as food items, can be seen and hunted. High humidity is required by tarsiers; if it is not supplied through circulating air, the animals should be misted several times a day. Tarsiers prefer to drink droplets from the misting on their fur and cage furniture, rather than to drink from dishes. To prevent injury, cage floors should be covered with litter 5 cm (2 in) deep, such as shredded cypress bark, which is resistant to decomposition and retains moisture. Nutrition Inasmuch as the prosimians are a highly diversified group of animals with extraordinary variation in dietary requirements, no general diet can be recommended. The group as a whole will not thrive on commercial diets standardized to meet the needs of New World or Old World monkeys. Many of their dietary needs are still not well understood. Therefore, maximizing dietary variety might prevent nutritional imbalance. The recommendations that follow are essentially descriptions of the most successful diets known at this time. The true lemurs can be maintained on a diet of monkey chow mixed with alternating selections of chopped fruits and vegetables. The gentle lemur (Hapalemur) eats the leaves and stems of several bamboo species and seems to prefer only particular vegetables, such as cucumber and sweet potato. It appears to extract nutrients more efficiently than other lemurs, and browse should be carefully screened for potential toxicants (e.g., oxalates in Russian vine). The ruffed lemur (Varecia ) is much more frugivorous and has a very short gut-passage time. Soft stools in these animals are firmed by the addition of browse to the diet. For the gentle lemur and mongoose lemur (Eulemur mongoz ), monkey chow should be restricted lest they tend to become obese and develop hypercalcemia. Mouse and dwarf lemurs (Cheirogaleidae) can be fed a combination of cracked monkey chow mixed with chopped fruit and vegetables and live crickets or mealworms. For the fat-tailed dwarf lemur (Cheirogaleus medius), the daily

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--> summer provision is a tablespoon each of the chow and vegetable-fruit mix with one or two crickets. The winter diet is reduced by one-fourth and crickets are eliminated. The lesser mouse lemur (Microcebus murinus ) can be maintained on the same diet by adding a cricket to both the winter and summer diets. Obesity will result if winter diets are not reduced. Mirza coquereli, in contrast, does not enter torpor (a period of lethargy resembling hibernation), and no dietary change is required. It will consume about twice the amount in the summer as the lesser mouse lemur. Indrids are obligatory folivores that have specialized in detoxifying various classes of leaf compounds, such as tannins. As a consequence, their captive diets require much more attention than that of other lemurs lest they quickly sicken and die. Sifakas pose particular problems in that they reject new items in their diet until they see and smell other conspecifics eating them. Leaf fiber (e.g., mango, sumac, mimosa, sweet gum, and tulip poplar) appears to be critically needed for their health. Deciduous leaves wrapped in plastic and frozen will be accepted after thawing. The seed pods and flowers of such plants as mimosa, redbud, and maple are also important food items, but they might cause diarrhea if introduced abruptly in large amounts. Browse is best presented by tying it to vertical supports. Peanuts and oak nuts should be limited because of their high fat content, but they are preferred foods, so they might help a sick (underweight) sifaka to recover from illness. Sifakas seem reluctant to drink water, and few will use a water bottle. Open bowls are more likely to be used, and browse can be sprayed with water. Aye-ayes will reject monkey chow even if it is mixed with honey, coconut milk, milk, or fruit juice. They have been successfully maintained on commercially available foods, including a wide variety of fruits, cucumbers, coconuts, corn on the cob, sugarcane, raw eggs, and insect grubs, such as mealworms, waxworms, and various wood-boring larvae. Raw eggs should be limited to no more than three times a week because of the biotin-binding properties of avidin in the whites. Vitamins can be added to a gruel made of sweetened condensed milk, high-protein baby cereal, and eggs. Insect grubs appear to be the most-favored food items, as well as foodstuffs that are high in sugar or fat. Aye-ayes are not seen to drink often, but they will lick water from a bowl by using their specialized third digit (Napier and Napier 1985, pp. 93–94). Lorises are adequately maintained on a diet of unsoftened, cracked monkey chow combined with chopped fruits and vegetables, crickets, and occasional mealworms. Separating feeding sites widely will reduce fighting over food. Yogurt and additional food should be provided to pregnant and lactating females. Lactation lasts for 6 months, but juveniles begin to eat solid food at 2–3 months. Galagos—and in fact all lorisids—need hard elements in their diet to remove tartar or plaque from their tooth combs and canines. If they are not provided or if the teeth are not cleaned, these accumulations can cause severe gingivitis, tooth

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--> loss, and eventual death. The presence of too much protein in the diet of lorisids can promote kidney disease. Tarsiers are strictly carnivorous and will not eat any kind of inanimate prepared food. In a typical night, a single tarsier will eat 30–40 crickets and perhaps one lizard. They will also accept mealworms, wild-caught insects, and laboratory-mouse pups. They also appear to need supplemental calcium, and crickets can be coated or dusted with powdered calcium or fed a diet rich in calcium before being introduced. Calcium paste can also be spread on tarsiers' thighs when they are sleeping, and they will later groom it off. Water should be supplied in bowls and as mist. Social Behavior Except for the relatively small number of species that do not consort as family groups (such as the mouse lemur, aye-aye, lorises, and some kinds of galago), prosimians do best when housed in social groups. All are highly sensitive to chemical stimuli (Schilling 1979). Scent glands often are sexually dimorphic and can undergo seasonal changes in activity (Epple 1986; Schilling 1979, 1980). There is great complexity in the scent-marking behavior of some prosimians, including elaborate mixing and dispersal of odorants from several sources (Evans and Goy 1968; Jolly 1966). Behavioral observations and several experimental studies have shown that secretions yield detailed information about scent donors' species, subspecies, gender, individuality, and hormonal status, as well as the age of the scent mark (Clarke 1982a, b; Dugmore and others 1984; Epple 1986; Harrington 1976, 1977; Mertl 1975; Schilling 1979, 1980). This information is important in many contexts, such as territoriality, reproduction, and social hierarchies. In the solitary species, chemical signals seem to be the predominant means by which animals communicate and by which breeding activities are coordinated (Charles-Dominique 1974; Schilling 1980). Moreover, in at least one species, urinary odors have been shown to influence endocrine events. Odors from dominant male mouse lemurs decrease testosterone concentrations and increase cortisol concentrations in isolated, unfamiliar males (Schilling and Perret 1987; Schilling and others 1984). Such priming might not be limited to the mouse lemur, but might occur in males and females of some other prosimians as well (Epple 1986). The high degree of reliance on chemical communication means that prosimians should be maintained in housing that permits them to engage in scent-marking activities, explore the scent of conspecifics, and maintain their own scent environment. Scent marks seem important to their well-being and might influence the reproductive physiology of conspecifics (Schilling 1979; Schilling and Perret 1987). Frequent and too-thorough cage-cleaning might be highly disruptive to their well-being. As with the callitrichids, cage-cleaning schedules should consider both the need for sanitation and maintenance of the animals'

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--> olfactory environment. During scheduled cleanings, it might be wise to leave at least some perches untouched until the next scheduled cleaning. Reproduction and Development Unlike other primates, prosimians have a primitive bicornuate uterus and, with the exception of the tarsier, have diffuse rather than hemochorial placentation. Breeding patterns vary from extremely narrow seasonal to a seasonal breeding. Gestation varies from as short as 2 months in mouse lemurs to 6 months or more in lorises, indrids, and tarsiers. True lemurs typically have brief, distinct breeding seasons. Males might fight one another during this time. Gestation lasts 4–4.5 months. Infants develop rapidly but might nurse for 4–6 months. Most mothers carry young infants, but gentle lemurs might ''park" infants on a branch while feeding nearby. Whereas most species breed in social groups, the mongoose lemur (Eulemur mongoz) and red-bellied lemur (E. rubriventer) breed as single pairs. Dwarf and mouse lemurs are usually found alone, but males seek out ovulating females. It is believed that males need olfactory or other contact with females to reach optimal breeding condition. Males constantly mark any clean surface during breeding, and excessive sanitation of cages interferes with breeding by the male. Females build nests where the young are born; Mirza builds a leafy nest, and the others nests in tree holes. As many as four infants can be born in a litter, but females abandon or cannibalize their young if cages are moved or cleaned while infants are in the nest. The vaginal openings of females often "seal" between estrus cycles. Gestation ranges from 2 to 3 months. Obesity interferes with reproductive cycling in sifakas (Propithecus ) and precautions to regulate calorie availability might be necessary with these animals. Singleton births are the rule, and care should be taken to keep periparturient females in warm environments because newborns have very thin hair and chill easily. Sifakas are the only lemurs whose birth period occurs in winter in the Northern Hemisphere. Other adult females and juveniles might interfere with newborns, so it is advisable to separate periparturient females for up to a week. It is, however, desirable to maintain visual and olfactory contact with other group members. After a week, mother sifakas will not allow other group members to steal or harm their infants. Fathers might at times carry infants but should be allowed to do so only if an infant can actively rejoin its mother. Weaning of infants occurs at 3–4 months. The gestation for Propithecus is 170 days. An aye-aye male might join a female for a few days at the time of ovulation and even sleep on or near her nest, but he otherwise remains at a distance. After a 5.5-month gestation, an infant will remain in the nest for nearly 2 months unless its mother carries it in her mouth to a new nest location. Galagos can take 2 or 3 years to resume breeding after being moved north of the equator. Galagos are less seasonal than lorises, but the vagina in both can seal

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--> until the week before estrus. Most can be kept as pairs for breeding, and even usually incompatible males can be safely placed with an estrous female. Males, however, should be removed from the room when females are ready to deliver and not returned until infants are welldeveloped. If left with a female, a male will cannibalize infants and, if left in the same room, might so stress a female that she will attack her own infants. Gestation periods are 5.5–6 months in lorises and 4.5 months in galagos. Although tarsiers will breed in captivity, they rarely survive the first week. Gestation is 6 months, and infants can weigh nearly 25% of the adult female's weight. It is thought that the failure of infants to thrive is due to dietary inadequacy. Cognition Little work on lemur cognition has been published, and the general impression is that these animals are less ingenious than other primates. Nevertheless, they display similar abilities in reconciliation after fighting and have complex vocal repertoires. Housing of dwarf and mouse lemurs can be enriched by constructing cages with many internal branches and chambers that are connected by tunnels so that animals can range throughout considerable space and have both contact with conspecifics and the ability to avoid them. Enrichment devices in the form of puzzles excite little interest in lemurs. However, food puzzles that require efforts in foraging do seem to attract their interest. The indrids will make use of swings and ropes and respond to food extraction puzzles. Although often passive, sifakas can be ingenious and manipulative when challenged in searching for food. The aye-aye has a more convoluted brain than other prosimians and well-developed foraging capacities that involve coordination of the senses. Hearing is extremely acute, and the third digit on the forelimb is elongated and specialized for probing and percussive tapping. Enrichment can be provided through puzzle feeders, logs that contain grubs, and relatively frequent cage-furniture rearrangement. Lorisids are inquisitive about their surroundings and seem to enjoy novel objects, such as wire mazes that contain fruit. Having live prey to hunt also greatly interests lorisids. Slender lorises will catch fish in water and stalk insects, birds, and small mammals. Gum-arabic feeders and such unusual food items as yogurt, eggs, and novel insects elicit the attention of all lorisines. Tarsiers seem to be lacking in responsiveness or inquisitiveness, but they do seem to appreciate complex cage interiors. Providing the widest possible variety of prey items also elicits fuller expression of their hunting regimen. Housing of tarsiers alone is inadvisable because it leads to inactivity. Same-sex pairs can show hostility, but groups of as many as six or seven can be formed without apparent conflict.

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--> Personnel Most prosimians are not aggressive toward humans, but caregivers might find it startling when an aye-aye jumps toward them or even clings to them. They are quite fearless and extremely inquisitive and will examine hands, head, feet, etc., in detail. Nonaggressive prosimians, however, will strenuously resist restraint. Sifakas can deliver powerful kicks, the aye-aye has a powerful bite, lorisids are adept biters, and the slow loris even has a poisonous mix of saliva and glandular secretions. During capture or restraint, many prosimians will resist vigorously with some peril to both handler and animals. Violent leaping and struggling in nets can produce self-injuries in indrids, and tarsiers seem especially stressed by handling. A minimum of restraint should be used, and personnel should be mindful of the fragility of the smaller species. Capturing animals while they are asleep in nest tubes or boxes is preferable to vigorous chasing. Veterinary Care Whereas most prosimians exhibit few health problems, some special comments are in order. Infants that are rejected by their mothers and hand-reared are notoriously sickly. Whenever possible, rejected infants should be fostered on another mother; lemurid mothers can easily rear two young at once. As a health precaution, lemurids should be weighed at least twice a year and whenever they are handled or there is concern for their health. Minimal interference in groups in large enclosures is possible. Lemurids readily recover from moderate trauma, and even simple fractures have been noted to have healed without treatment (although we do not advocate ignoring such injuries). When injuries (e.g., lacerations, fractures) require treatment, every effort should be made to provide treatment that will allow the animal to be returned immediately to its group. That will minimize the possibility of group rejection, which might occur after a separation of only 1 or 2 days. Substantial effort should be made not to separate sick or injured lemurs from their social group, lest separation cause depression or social rejection. Weight checks will reveal normal seasonal weight changes associated with winter torpor, but the weight of mouse and dwarf lemurs should otherwise be stable among adults. Fecal examinations (flotation and smear) should be carried out twice a year or whenever stool is abnormal. Newly arrived animals should receive fecal examinations weekly for at least 3 weeks. Stress produced by overcrowding sometimes leads to illness, especially liver and kidney problems. Sifakas are very susceptible to changes in diet, which can lead to diarrhea. Trichomoniasis can be a secondary problem with such diarrhea and requires treatment with metronidazole. Diarrhea and other septic conditions in indrids

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--> lead quickly to electrolyte disturbances, so quick and aggressive intervention is warranted. Intravenous fluids are the mainstay of such intervention; monitoring of intravenous fluids is essential because they tend to sequester in the large intestine. Third-generation cephalosporins are preferable to aminoglycosides in these animals. Because of the fermentative processes in their digestion, injectable antibiotics have to be used. Sick sifakas, if possible, should be paired with or kept in sight of other conspecifics to avoid anorexia and depression. Inasmuch as much of their bodily fluid is extracted from ingested plants, anorexia quickly leads to dehydration, electrolyte imbalances, and death. Sifaka are extremely sensitive to acepromazine, which causes almost immediate apnea and should never be used for sedation. Aye-ayes are generally hardy, and adults weight about 2.5–3 kg (5.5–6.6 lb). They might continually scratch at cuts or scrapes, especially about the face, and this greatly delays healing. Kidney failure and liver failure are frequent causes of death in lorisids and are perhaps diet-related. Fecal examinations should be conducted twice a year. Lorisids fight each other with attacks to the head, genitals, and tail, and the bite wounds are very likely to develop Pasteurella abscesses. Stressed mothers might overgroom infants. Much more than lemurs, lorisids require isolation from stressful factors. Sources of stress include the presence of too many cages in one room with consequent high levels of calls and vocalizations. Technicians should avoid disturbing nursing mothers. Stress is also contributed to by cages that are too small. Signs of stress include urine burns and overgrooming, which leads to hair loss. Tarsiers seem to be susceptible to severe ketosis, which might be age-related and appears unresponsive to medical treatment. Nutritional factors and the need to eat only live food affect the course of illnesses, because the animals stop feeding when weakened by illness. Pesticide residue can be a contributing factor to high infant mortality and loss of health. Tarsiers seem to be unusually sensitive to pesticide residue because of their diet, which is composed largely of insects, so every effort should be taken to keep their environments free of such substances. Special Considerations Lemurids are sensitive to Toxoplasma and Yersinia, and every effort should be made to keep these organisms out of their enclosures. Fecal material from cats and poultry are likely vectors, and Yersinia thrives in standing pools of water. Yersinia can be controlled by preventing the formation of standing water pools in runs. Ruffed lemur females, and other lemurs less often, sometimes neglect their young, especially when they are first-time mothers. They can be encouraged to "bond" with and nurture their infants by placing both mother and infants in a

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--> small kennel after parturition where the mother cannot stray from the young, and mothers will usually allow infants to be pushed underneath them by technicians if they stray too far. Cheirogaleid odors are often very powerful. Coquerel's mouse lemur has a particularly pungent and penetrating odor; it is normal for the species, and strong odors do not indicate unsanitary conditions. There is no evidence that air exchanges of more than 10 per hour improve this condition. Indrid mothers can be aggressive to infants during weaning, and this is a critical period when a juvenile can rapidly dehydrate and die because of insufficient fluid intake. Intervention involves administration of subcutaneous or intravenous fluids (not oral fluids). As stated earlier, sick indrids should not be kept in small cages for extended periods. For proper health and reproduction, indrids seem to need outdoor access. Unlike all other prosimians, aye-ayes actively bite into wooden structures in cages. When they are to be transported, it is advisable to line the inside of airline kennels with wire. Both lorises and galagos need a fairly high relative humidity (50–60%) to avoid peeling and cracking of the skin. If their cages have insufficient or inappropriate surfaces for marking, lorisids (especially males) suffer urine burns. Ventilation and drainage holes should be drilled into the bottom of PVC nest tubes. Lorises and galagos might urinate in these tubes while sleeping and can develop urine scald if the urine is not allowed to drain. For that reason, some caregivers prefer sleeping boxes made of wood, which is more absorbent. When transported in large cages, tarsiers sometimes died from injuries sustained because of their great leaping capacities and general excitability. It has been found that a very small cage—–20 x 12 x 14 cm (8 x 5 x 6 in)—with screensided panels protects them. Each box can contain two vertical dowels in central positions. The animals cling to these dowels but cannot jump. Tarsiers are very easily dehydrated, and lack of humidity can cause desiccation of the skin of digits or tail and lead to loss of all or part of these extremities. Humidifying procedures are therefore mandatory.