Abstract: Marmosets and tamarins are small New World primates that are very susceptible to many diseases, including viruses of other species of nonhuman primates and man. They require a specialized diet and have high vitamin D3 requirements. Diarrhea is a common condition and may require intensive therapy, but it can prove fatal. These primates are very gregarious animals.
Small animal veterinarians, especially those who treat birds, reptiles, or other exotics, may occasionally be called upon to examine and treat unusual species of animals not often kept as pets. Some exotic animals are purchased for uniqueness with little thought given to how to care for them. As a veterinarian, it will be beneficial to know some basic information about the care of callitrichids, marmosets, and tamarins, as they are increasing in popularity as pets. If you are interested in treating callitrichids in your practice, please check all requirements from regulatory agencies to ensure that you are compliant.
Marmosets and tamarins are small South American monkeys that are members of the callitrichid family. All are considered threatened in the wild, and many are endangered. Because of their appeal, people are interested in owning them as pets. Hand-raised, bottle-fed babies are quite charming, but with the onset of sexual maturity, they become unpredictable, aggressive, and dangerous to humans-including their owners. Consequently, people should be discouraged from keeping them as pets.
If a client is set on owning a callitrichid however, he or she should be steered toward a tamarin instead of a marmoset as they tend to have more stable personalities as adults and are not as aggressive or unpredictable. Marmosets have adorable faces, and are very appealing, with many facial expressions, which attract people. Tamarin faces are less hairy than those of marmosets, and appearance-wise, they are not as attractive.
In the wild, callitrichids live in family groups consisting of a dominant female and a dominant male. The dominant female secretes a pheromone that suppresses ovulation in the other females in the group. Callitrichids appear to have an estrous cycle as opposed to a menstrual cycle, as occurs most other primates. This cycle is approximately 15 days in most species. Callitrichids become sexually mature at approximately 16-25 months of age; however, copulation and masturbation may occur much earlier. The gestation period is approximately 150 days. A postpartum estrus occurs 9-10 days after parturition. There are distinct mating and birthing seasons.1
People often ask about the differences between marmosets and tamarins. The differences can be classified in 2 different ways. First, taxonomists distinguish the differences between marmosets of the genus Callithrix and tamarins of the genus Saguinus by their teeth. The incisors of marmosets are enlarged, so that they are the same length as the canines which enables them to gouge holes effectively in trees so as to consume the nutritive gums and saps (called exudates). The canine teeth of Saguinus species tamarins are longer than the incisors,1 which means that they can inflict a deeper bite. Because of the differing lengths of the tamarin's teeth, some government organizations have classified tamarins as more dangerous animals than marmosets. While the tamarin's teeth may allow a deeper bite, it is the innocent-faced marmoset that is much more likely to chomp a human's face, ear, or nose! This defines the other way that marmosets and tamarins may be differentiated. As far as aggression goes, it is the marmoset that is usually more aggressive and dangerous! Hand-raised marmosets are quite fearless around humans. They may actively and aggressively defend their territory and their owner against strangers and family members. They may quickly jump to a visitor's shoulder, then launch an attack on the face or ears. They usually bite quickly, but the bite is prolonged, meaning that once they bite, they do not let go. Sometimes, they bite, and keep chomping down, causing multiple bite wounds in the same area. Other marmosets bite toes, hands, or knees as the preferred sites. On occasion an enraged marmoset may bite its owner in a case of misplaced aggression when it sees a person it considers a threat. A tamarin may also attack strangers or a person it perceives to be an intruder to its environment, and it also may bite family members that it does not like. A hand-raised callitrichid is quite fearless around humans.
Marmosets are in the genus Callithrix. Depending on which taxonomist you consult, there are 3, 9, or 12 species. Some species overlap in certain regions in South America, resulting in intergrades or hybrids (although this term is usually not used in regard to marmosets). For example, the black tufted-eared marmoset (Callithrix penicillata) and the common (or cotton-eared) marmoset (Callithrix jacchus) overlap in an area in southern Bahia. A marmoset in the overlapping area may be considered a hybrid, a sub-species, or a separate species, Callithrix kuhli. There are intergrades between other Callithrix species, as well. The Geoffroy's marmoset (C geoffroyi) also shows intergrades between C penicillata and C jacchus, where the ranges overlap.1 The other marmosets include the pygmy marmoset, (C pygmaea), C aurita, C flaviceps, C argentata, C humeralifer, C mauesi, and C nigriceps. The Goeldi's monkey (Callimico goeldi) has its own genus and species, and it is quite different from the Callithrix group as it usually has only one offspring at a time, and has many anatomical and physiological differences, as well.
Most of the tamarins commonly seen by veterinarians and kept in captivity are members of the genus Saguinus. The red-handed tamarins (Saguinus midas) is threatened in its range in Surinam. Of all the tamarins, this author believes that the red-handed tamarin has the best pet qualities. The cotton-topped tamarin (S oedipus) is endangered, as defined by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (IS), Appendix One. With its shock of white hair sticking straight up on the top of the head, it is quite striking. The Geoffroy's tamarin (S geoffroyi) is also endangered, and in this author's experience, difficult to successfully breed. The moustache tamarin (S mystax) is primarily black, with white hair on the upper lip, which creates a moustache-type appearance. The emperor tamarin (S imperator) is a spectacular creature with long, white hair that looks like a handle-bar moustache. Other tamarins are the saddle-backed tamarin (S fuscicollis) and the white-mouthed tamarin (S nigricollis, S labiatus, and S bicolor). There are other species of Saguinus tamarins, as well. The well-known golden lion tamarin (Leontopithecus rosalia), black lion tamarin, (L chrysopygus), black-faced lion tamarin, (L caissara), and the golden headed lion tamarin, (L chrysomelas), are endangered beautiful monkeys.
Callitrichids communicate by high-pitched tones, varying from chirps to loud, shrill whistles and screeches. Vocal communications between individuals occur in frequencies above human hearing and they also produce audible vocalizations. The audible sounds used for communication have been studied extensively in cotton-topped tamarins. Because they are arboreal, which limits visual communication, they have evolved complex vocal communication systems.2
Marmosets may present tumescent genitalia from behind, and females may display, as well. Marmosets will turn away from perceived threatening people or potential enemies, raise the tail and at the same time, raising up on the hind legs, present their genitalia to the object of their display. Back arching is another behavior. This is a sign of aggression, as is tongue flicking. Tongue flicking and head shaking may precede an attack. Mature callitrichids can be territorial and aggressive.1
Neutering: It has been proven that neutering callitrichids will not decrease aggressive behavior and biting. Please do not neuter endangered species in an effort to make them better pets. If the time comes that a neutered callitrichid need to be placed in a sanctuary, it will be lost as a potential breeder. Removing canine teeth to make bites less painful is cruel and dangerous. There is a possibility that the jaw may fracture and it will cause malocclusion. Filing teeth down will leave the pulp cavity open to infection, and should be avoided. Declawing should also never be performed as this will prevent natural climbing and may affect the ability to properly hold food in the hand.
The mean body temperature of callitrichids lies between 37-38° C.1 The average life span of a marmoset in captivity is approximately 12 years, and for a tamarin, it is 17 years.1 The smallest marmoset is the pygmy, with an adult weight of about 130 g.1 Age at first birth may be as early as 20-24 months, but sexual maturity is reached at 12 months for the female, and 16.7 months for the male.1 Callitrichids possess a duplex retina, consisting of both rods and cones, so they do see color.1 They rotate the head from side to side to better estimate distance. The uterus is simplex unlike the bicornuate uterus of the dog and cat.1 The placenta is labyrinthine and the attachment of the umbilical cord is discoidal or bidiscoidal in the case of twins.1 In twins, usually 1 embryo is attached to each of 2 placental disks.
Males have a baculum. Chimerism is a normal phenomenon in callitrichids in which polyzygosity, usually dizygosity, occurs. Chimerism can be readily detected in heterosexual twins by the presence of both male and female sex cells in the tissues, especially hematopoetic and gonadal tissues.1 The common marmoset has a cecum specialized for digesting plant saps and gums (exudates).
Marmosets usually have twins, but triplets and quadruplets also occur. Tamarins usually give birth to twins, but triplets also occur occasionally. Goeldi's monkeys usually have singletons. If parents have not been raised in a family group (if they have been hand-raised), they will not have acquired parenting skills by participation in carrying and caring for siblings born after them and they may not have the necessary skills to successfully raise their offspring. However, after several birth cycles hand-raised callitrichids may correctly care for their young. Singletons in most species often result in dystocia, as a single baby may be very large.
Breeders hand-raise marmosets and tamarins in an effort to produce better pets. However, one must realize that these are wild animals and are not domesticated. Breeders remove infants from their parents for hand rearing when they are between 3-10 days of age which allows the infants to receive colostrum and milk that contain antibodies. Infants are delicate and each twin usually weighs between 28-35 g at birth. While the eyes are usually open at birth, occasionally one or both eyes will remain closed for as long as 3 days. This symblepharon does not usually require veterinary intervention. The milk teeth are erupted at birth. Infants have a distinctive juvenile pelage. They have less hair on the ventral chest and abdomen to better allow transfer of body heat to them from family members that carry them. They have hairs on their fingers that interdigitate with the hair of family members, so they better grip them. Babies are born with strong forearms for holding parents. It is very difficult to remove a healthy baby from an adult. Baby teeth have all erupted by approximately 27.5 days of age. Adult molars erupt around day 112 (16 weeks). The last permanent teeth to erupt are premolar 2 and the canines, at approximately 340 days of age (48 weeks).1
Babies cannot thermoregulate for the first 2 months. The father carries the infant the majority of the time. The female usually only carries the infant to nurse it after the first 10 days. The baby normally rides across the parent's neck and shoulders. A good indicator of whether the baby is healthy is by observation of the tail. Tamarin babies carry their tails tightly curled when healthy; if the tail is straight and limp, the baby is in trouble. Marmoset babies hold their tails tightly against the parent's body. Again, if the tail is limp, the baby is in distress. If a baby has a limp tail and is consistently riding low on the parent (below the shoulders and neck), it should be removed from the parents for examination and evaluation. A weak, hypothermic, malnourished, or injured infant will have a limp tail.3 This indicator also works to assess a baby being hand-fed.
Hand-raising a baby callitrichid requires an incredible amount of devotion, time, and emotional energy. To simulate their natural lives, the owners should carry infants as often as possible for warmth and emotional security (after the crucial first 2 weeks when they should be kept in a temperature controlled environment, such as a brooder). Keeping a baby on a stuffed animal surrogate for extended periods is unnatural and cruel. Infants need the stimulation and affection afforded by constant contact. Motion encourages the connections of neuronal pathways, and babies carried often will develop motor skills more quickly than those left on a surrogate for extended periods of time.
If a baby must be placed for short times on a surrogate, an insulated soft-sided six-pack cooler, with a microwavable soft heating pad under a stuffed animal, works very well. Plug-in type heating pads should not be used because if the baby crawls between the stuffed animal and the pad, it can quickly overheat and die even if the heating pad is set on the lowest setting. "Beanie baby"-type stuffed animals are a good choice, as the plastic beads retain heat and will help keep a baby warm. For the first 2 weeks, newborns should be maintained within the temperature range of 37.2-38.3°C (99-101° F). The baby should feel slightly warm to the touch. If a baby is too cold, the extremities will feel cool to the touch and it will be lethargic Infants need to be stimulated by gentle patting of the perineal area to stimulate urination and defecation.3 Babies will begin to spontaneously urinate and defecate by the third week.
It is important to weigh a baby the day it is removed from the parents. It should then be weighed daily, preferably in the morning. A healthy baby should gain weight daily, but it may remain at the same weight for the first day or two, which is usually not a problem as long as the baby is acting normally. Infants that have had their tails chewed off by parents, or those bitten and mutilated, will not gain weight for the first week of life, or maybe longer.3 Injured babies should receive antibiotic therapy for at least 10 days after the injury. Cephalexin (25 mg/kg PO q12h; Cephalexin for Oral Suspension, Qualitest Pharmaceuticals, Inc, Huntsville, AL, USA) or Augmentin (15 mg/kg q12h; Augmentin for Oral Suspension, SmithKline Beecham Pharmaceuticals, Philadelphia, PA, USA), based on the amoxicillin component, are good first choices for antibiotic therapy. Watch carefully for any signs of thrush (oral candidiasis), and treat as needed.
Infants should be fed a commercially available human baby formula with normal iron levels, such as Enfamil (Enfamil With Iron, Mead-Johnson Nutritionals, Evansville, IN, USA) in the can with the yellow label.3 While this formula is available in both powdered and liquid forms, this author recommends using the powdered formula to prevent waste. The unused liquid formula should be discarded after 48 hours. Recently, this company developed a baby formula especially for premature infants (green label), (Enfamil 22, Mead-Johnson Nutritionals) and this formula is higher in nutrients, and it works well to feed newborn callitrichids. However, because it is not available in all areas, the formula with the yellow label is still recommended. Enfamil Low Iron (Mead-Johnson Nutritionals) with the pink label, which is low in iron, should be used for babies suffering from constipation. Iron may be constipating, so feeding the low iron formula may be helpful in those cases. Enfamil Lacto-Free (Mead-Johnson Nutritionals) with the purple label can be used for babies diagnosed as lactose-intolerant. This can be presumptively diagnosed by ruling out other causes of diarrhea and colic. Other diets have been developed for specific infant conditions, and these can be used for appropriate occasions (pre-digested formula, soy-based formula, etc). Once a week, a drop of pediatric multivitamins (Poly-Vi-Sol, Mead-Johnson Nutritionals, Evansville, IN, USA) should be mixed into the formula. Formula should be warmed to about 37.8° C (100° F) before feeding. This author recommends using bottled water to prepare the formula to prevent contamination with potential pathogens (unless the tap water is boiled).
Newborns should be fed every 20-30 minutes for the first day. By day 2, infants should be fed every 2 hours around the clock (or on demand) and must be stimulated in the perineal area to urinate and defecate. Day 1 marmosets usually consume between 0.2-0.5 ml per feeding and will increase the amount by about 1.0 ml per feeding per week. Day 1 tamarins usually consume between 0.5-1.0 ml per feeding; this amount increases by approximately 1.0 ml per feeding each week. Each day, intake should increase by a small amount per feeding. For example, a two week old tamarin will usually consume approximately 2.0 ml per feeding. Babies usually begin sleeping through the night when they are 2 weeks old and will not require night feedings. Babies will usually begin showing an interest in solid food at about 3 weeks of age. At that time, baby cereal, fruit juice, and strained baby food can be slowly added to the formula. Weaning may occur at about 8-10 weeks of age, but in the family group, the babies may nurse until the next infants are born (if they are born 5-6 months after the previous birth). Weaning foods designed for human children are good early foods (go to the toddlers section of the grocery store). If youngsters are eating solid foods well, it is acceptable to provide a bowl of formula twice daily for nutritional supplementation as long as it does not cause diarrhea.3
Young marmosets and tamarins nurse for as long as 3 months in captivity and the babies often run to the parents and jump on a family member's back when frightened. A bottle-fed baby will run to its surrogate mother and climb up onto the head when frightened. Youngsters become independent at between 3-6 months of age, but will stay with the family group for an extended period.
Diarrhea is common in neonates. Treat based on culture and sensitivity of the stool. Often the diarrhea is caused by Clostridium species, and it responds to treatment with a combination of metronidazole (Flagyl Oral Suspension, 50 mg/ml, Rhone Poulenc Rorer, Jose Ma. Rico, Mexico) dosed at 35-50 mg/kg/day PO divided into 3 doses, administered for 7-10 days given in combination with trimethoprim/sulfamethoxazole (Bactrim Pediatric Suspension, 48 mg/ml, Roche Laboratories, Inc, Nutley, NJ, USA) dosed at 48 mg/kg/day divided into 2 doses PO q12h. The metronidazole is efficacious against clostridial organisms, and the sulfa is used to treat related colitis. For symptomatic treatment of diarrhea, treat with attapulgite (1-2 ml/kg PO q6h; Donnagel, Wyeth Laboratories, Inc, Philadelphia, PA, USA). If the neonate is becoming dehydrated, consider subcutaneous administration of lactated Ringer's solution, as needed.
An appropriate diet is important for callitrichids to remain healthy in captivity. Marmosets and tamarins are extremely intelligent and should be fed a rotating diet to prevent boredom. Callitrichids are among the most omnivorous and opportunistic feeders of the nonhuman primates. Most species consume gums and sweet saps produced by trees. They gnaw on the bark and may strip it from trees, or they may chew twigs. It appears that the gums and saps fill a nutritional requirement not always present in other available foods. Marmosets are considered to be gumivores and tamarins are seasonal gumivores. The common marmoset (Callithrix jaccus) consumes more gums in the wild than any other marmoset (15% of the diet).1 Because of their unique niche in feeding, callitrichids present somewhat of a challenge when it comes to providing them with a nutritious and balanced diet in captivity. Most wild callitrichids naturally consume fruits, a high percentage of insects and small vertebrates, eggs, nectar, flowers, other types of seeds, buds, green shoots, and as much as 15% gums and plant exudates, which contain high levels of calcium and crude protein. They may gorge themselves on vegetable matter alone or on crickets, a mouse, a bird, a lizard, a frog, or various combinations of anything considered edible by callitrichids.1
The base of the diet for captive callitrichids should be canned marmoset diet (Zupreem, Premium Nutritional Products, Inc, Mission, KS, USA) supplemented with primate biscuits. Yogurt (live culture), raw peanuts, bananas, chopped broccoli or carrot, cucumber, cooked yams, corn on the cob, apples, grapes, peaches, plums, eggplant, celery, papaya, mango, cooked beans, raw string beans, cooked pasta, fruit ring breakfast cereal, and cooked oatmeal can be fed daily. Kibbled dog food and cat food can be added to the mix periodically. Scrambled eggs, cooked meats, deli meats, hard boiled eggs, cottage cheese, other types of cheese, tuna, artificial crab, and cooked shrimp are good protein sources. Crickets, mealworms, and waxworms can be fed periodically.3 Ingestion of mealworms may cause transient diarrhea. Always feed high quality insects.
Onions have been shown to cause Heinz-body hemolytic anemia in other species of animals, and there have been anecdotal reports of this occurring in baboons (Cathy Johnson-Delaney, oral communication, August 1997). It is probably safest to not offer onions or onion products to callitrichids, because they possess no necessary nutrients that cannot be found in other foods. Read labels closely, because some children's foods, such as chicken sticks (Gerber Graduates Chicken Sticks, Gerber Products Co, Fremont, MI, USA), contain onion powder to increase palatability. While the amount of onion powder in these foods is probably quite small, they should not be fed in excess.3
Nutritional enrichment
Hiding insects in shredded paper, wood shavings, or dry oatmeal can supply needed enrichment, allowing callitrichids to forage. In the wild, callitrichids spend as much as 60% of their day foraging and rarely encounter abundant food. Distributing food throughout the day and making it harder to find helps to simulate a more natural situation. Holes may be drilled in wooden perches or dowels, and food items inserted into them; such foraging devices simulate extractive foraging behavior and stimulate the primates' skills. Another device that allows increased time to be spent in food acquisition involves whole apples, oranges, corn on the cob, or other foods, which are speared onto the end of a stick suspended from a branch in the cage. Food items, thus suspended, may be picked at by callitrichids as they hang by their hind legs.4 Treat cups on a chain with a lid and peek holes, designed for birds, may be used to hide relished food items.
Callitrichids relish sweets and may be treated to small quantities of marshmallows, Gummibears (Trolli Gummi Candy, Trolli, Inc, Plantation, FL, USA), cake, pudding, cookies, and animal crackers. It is often a good idea to hand feed a marshmallow or candy before sunset to ensure that callitrichids are eating and will have some sugar in their system prior to retiring for the evening. Nonhuman primates can consume small amounts of milk chocolate products with no apparent ill effects. Many research facilities have used M+M candies (Mars, Inc., Hackettstown, NJ, USA) as treats. As a supplement, they should receive one-quarter of a 250 mg chewable vitamin C tablet (Natural Vitamin C and Rose Hips, Nutrition Headquarters, Carbondale, IL, USA) daily, as well as a drop of a pediatric oral liquid vitamin (with vitamin D3) (Mead Johnson) or a chewable children's vitamin daily. Nutri-Cal (Nutri-Cal, Evsco Pharmaceuticals, Buena, NJ, USA) can also be fed daily and is an excellent nutritional supplement for an anorexic callitrichid.
Callitrichids like to sleep in a box where they feel secure. They prefer to sleep high and like to have towels, blankets, and stuffed animals to snuggle up to. Most go to sleep at sunset. They are active and require a cage large enough (3 ft X 3 ft X 4 ft would be adequate [approximately 1 m X 1 m X 1.2 m]) for them to jump and play. The cage should be as large as possible. There should be a wood perch in the cage to allow callitrichids to gouge holes in the wood with their teeth, performing a necessary behavior that also serves to keep the teeth clean and gingiva healthy. Toys, ropes, swings, and other cage equipment should be provided for exercise and playtime. Callitrichids will drink out of sipper tubes and water bottles. Food may be offered in a sturdy bowl. Newspaper is an adequate cage bottom substrate. Many owners allow their callitrichids to run free in the home, but a cage is still recommended to confine a pet when guests visit.3
Callitrichids are intelligent and need stimulation. Interaction can be supplemented with toys, but if a callitrichid is kept singly as a pet, it will rely on the human family to become its family group. If a callitrichid must be kept alone for periods of time, the cage should be placed by a window, television, other caged pets, or an aquarium of fish.
Lighting: If at all possible marmosets and tamarins should spend some time outdoors during warm weather so that they are exposed to natural sunlight. Callitrichids have very high vitamin D3 requirements, and may suffer from nutritional secondary hyperparathyroidism unless this is supplemented in the diet, and unless they are exposed to ultraviolet light. Callitrichids housed indoors should have full-spectrum fluorescent lights close to the cage; lights should be changed every 6-9 months. Callitrichids should be allowed access to natural sunlight as often as possible.
In callitrichids, the use of olfactory signals and pheromones is highly developed. They have numerous scent glands. The glands of the interramal, gular, sternal, abdominal, and inguinal areas mark runway branches. They use circumgenital glands to mark selected objects and their mates by swaying their posterior in a side-to-side motion on the object. The ulnar-carpal glands leave scent on anything brushed against the arm. All glands imprint the offspring with the odor of the parents, family group, and race. They scent mark their areas by rubbing the perineum over everything: toys, food dishes, bedding, stuffed animals, furniture, rugs, and caging. Scent marking is used for identification of a breeding pair and their offspring and for assertation of social status, sexual readiness, and territorial claims. It is also used to invite and to repel, as well as to countersign the markings of others. Some tamarins mark by urinating into the hand and may rub their cheeks in the urine of their sexual partners.1 Marking in cotton-topped tamarins (Saguinus oedipus) occurs with much greater frequency in females than males. Marking may vary significantly between different species. These monkeys are not particularly messy animals and can be somewhat trained to defecate in a given area. Their urine is not very strong, and they tend to urinate frequently in many locations.
Pet callitrichids should have annual physical exams and stool cultures. It is important that the clinician specifically request culturing for Salmonella, Shigella, Campylobacter,and Yersinia. Feces should be examined for protozoa, such as Giardia species. Blood work may be indicated. Humans with viral infections should not be allowed near marmosets and tamarins as a safety precaution lest the infection be contagious to callitrichids. Some tamarins have demonstrated titers against influenza virus without becoming clinically ill. Measles can also be fatal to callitrichids. If a callitrichid will be around children, it should be vaccinated against measles. A vaccination against tetanus is recommended for all callitrichids housed outdoors and may be a good idea for callitrichids housed indoors as well.5 It is possible to have callitrichids screened for specific viruses.
Human cold sores, caused by the Herpes simplex virus, are extremely dangerous to marmosets and tamarins, and may cause a fatal encephalitis. It is important to realize that a human need not have an active herpetic lesion in order to transmit the virus to a callitrichid. Herpes encephalitis appears to be age-related, in this author's experience. Young marmosets and tamarins, less than 12 months of age, will usually die within 5 days of developing signs of illness (usually 3 days after exposure). Older callitrichids do not appear as susceptible to this infection (or they may develop an inapparent infection); however, that does not mean that people can be careless. Experimental vaccination has proven protective in guinea pigs, but studies in callitrichids have not yet been performed (Branson Ritchie, oral communication, May 1998).
Humans with HIV or other immune system suppressing diseases should probably not own primates due to the risk of transmission of a zoonotic disease to them by their pet.3 There is also the theoretical risk that the HIV virus may be transmitted to pet callitrichids, however, at this time, this has not been proven. Other human viruses may also occasionally cause disease in callitrichids (they are susceptible to arenaviruses, and possibly some rhinoviruses) (Col. Nancy Jaax, oral communication, May 2000). Other nonhuman primates, especially squirrel monkeys and spider monkeys may carry Herpes saimiri and Herpes ateles viruses respectively which can be fatal to callitrichids.5
Although tuberculosis is rare in New World primates, callitrichids can be tested for tuberculosis using the intradermal skin test using mOT tuberculin.6 There is some risk of damage to the eyelid or eyeball by using the usual eyelid testing site, so use discretion in choosing a location for TB testing (Richard Montali, oral communication, August 2000). This author does not recommend yearly tuberculosis testing for callitrichids, unless there is known exposure. Tuberculosis has rarely been diagnosed in callitrichids. Fortunately, most dangerous viral zoonotic diseases are found in Old World species, such as species of macaques.
Callitrichids, especially juveniles, should be handled by as few humans as possible. If callitrichids are taken out in public, people should not be allowed to handle or touch them, to prevent the risk of disease transmission to them. Also, due to the unpredictable nature of marmosets and tamarins, they can attack and bite strangers unprovoked, which may result in a lawsuit, or worse, rabies quarantine. This should be avoided at all cost. Marmosets tend to bite the face, ears, or hands, and they can be very quick. Once they bite, they tend to hang on and grind away.
Diarrhea is the most frequently seen medical problem, with the cause often multifactorial and often related to changes in the diet, stress, parasites, and bacterial infections from E coli and species of Salmonella, Shigella, Klebsiella, and Campylobacter. Kaopectate (0.25 ml P0 q6h; Children's Kaopectate, Pharmacia & Upjohn Consumer Healthcare, Kalamazoo, MI, USA) or Pepto-Bismol (0.2 ml P0 q6h; Procter and Gamble, Cincinnati, OH, USA) may help. Sucralfate (0.25-0.5 ml PO q6h; Carafate Suspension, Hoechst Marion Roussel, Inc, Kansas City, KS, USA), has proven effective in treating nonresponsive diarrhea. Diarrhea may become serious, even life-threatening. Cephalexin pediatric oral suspension (Qualitest), Bactrim pediatric suspension (Roche Laboratories), Flagyl (Rhone Poulenc Rorer), and Augmentin pediatric suspension (SmithKline Beecham) are accepted and palatable to marmosets and tamarins. Treat dehydration with SQ or intraosseous fluids if necessary.
Restraint methods of callitrichids are important skills to learn. Make sure a room is secure, with no hiding places, because if a callitrichid escapes, it will run behind anything it can, and it may be impossible to extract it. Nets are helpful to catch up a marmoset or tamarin. Gloves may be used, if necessary, but it is safer to handle one with bare hands (for the monkey). Grasping the monkey loosely around the neck, and then restraining the hind legs, works well. Remember that they have very dexterous hands, and may grab at equipment or fingers, pulling them towards their mouth and those sharp teeth. Isoflurane anesthesia (Forane, Baxter Pharmaceuticals, New Providence, NJ, USA) may be employed for examination if necessary, after ensuring that the callitrichid has been fasted for an appropriate period of time (usually 8-12 hr). Make sure to discuss anesthesia with the owner prior to performing any procedures.
Blood may be drawn from the femoral vein or the jugular vein, using only manual restraint. Catheters may be set in either of these veins as well. Intraosseous catheters can be utilized; however, they appear to cause significant pain in callitrichids. Their use should be considered if the animal will be sedated or receiving appropriate pain medication. Consider using sub-cutaneous fluids with hyaluronidase (Wydase, Wyeth-Ayerst Co., Philadelphia, PA, USA) at 150 units of hyaluronidase/l of fluid to facilitate absorption.
During an annual examination, the callitrichid should be weighed. A fecal culture should be performed (making sure to request that the lab screen for the common callitrichid pathogens: Campylobacter, Shigella, Salmonella, Yersinia, and Klebsiella). The stool should be examined by wet mount for protozoa, a flotation should be performed and the sediment should be examined for thorny-headed worms (Prosthenorchis elegans). Consider sending feces preserved in 2% formalin to Parasitology Research Lab, Inc. to have the feces examined. This lab performs 6 different stains to look for Giardia, cryptosporidium, microsporidium, and other parasites. An acid fast stain may be performed on stool. A CBC and serum chemistries should be performed. Whole body radiographs should be performed. Vaccinations should be discussed with the owner and appropriate vaccines should be administered.
Tetanus toxoid may be administered, usually every 2 years. Rabies vaccination is controversial. If given, always use a killed virus product. This author's USDA veterinarian advises against rabies vaccination in callitrichids. Rabies vaccination is untested in callitrichids so its administration should be decided by the veterinarian and owner. Canine killed rabies vaccines may be used (oral communication, Richard Montali, July 2000). Measles vaccination may be administered in cases where there is risk of exposure.6
During the yearly examination, the animal should be given a complete physical examination. The teeth should be examined and cleaned if necessary. Husbandry and diet should be discussed with the owner. As previously discussed it may not be necessary to TB test callitrichids routinely. If the callitrichid is part of a group owned by a facility licensed by the USDA, consult the USDA licensing veterinarian to get his or her input. Callitrichids are usually exposed to TB from human contact. Since this is a zoonotic disease, testing should be considered especially if there is risk of exposure.
Hospitalized callitrichids should be provided supplemental heat, a dark box for sleeping, and should be handled as little as possible. Favorite foods should be offered. If possible, allow owners to treat their pet at home, as they become depressed when separated from family members. Ill callitrichids often require immediate treatment. When possible, procure samples for lab testing and then begin treatment immediately. Do not wait until the tests are back. Callitrichids may be compared to birds when it comes to their illnesses. They do often hide signs of illness until they are quite ill. They are fragile with limited reserves (also like birds). A warm and quiet environment is essential. Water consumption is vital, so medication should not be administered in the drinking water since it might discourage drinking.
If a callitrichid does not survive, a complete gross necropsy should be performed. Tissues should be procured for histopathology, ensuring collection of the duodenum and pancreas in addition to the regular tissues taken for histopathology. The brain should also be collected for histopathology. Tissues may be frozen for viral study, if necessary. It should be noted that often intusseption of the intestines may occur post-mortem and should not immediately be mistaken as the cause of death (oral communication, Col. Nancy Jaax, March 1998). Appropriate precautions to prevent exposure to possible zoonotic disease should be taken by the veterinarian performing the necropsy.
Wasting disease: One of the most frustrating medical conditions encountered is "Wasting Disease," "Marmoset Wasting Syndrome," or "Wasting Syndrome." Signs include chronic, unresponsive diarrhea, rough hair coat, and alopecia of the tail. Paralysis of the tail and hind limbs may occur in the later stages of this disease. Mortality rates among marmosets and tamarins that develop wasting are high. Wasting is probably caused by a number of diseases, and may be multifactorial.5 One suspected cause is the pancreatic worm, Trichospirura leptostoma.8 The intermediate host is the cockroach. Any callitrichid that dies with signs of wasting should have histopathology of tissues performed and the duodenum and pancreas should be harvested. The pancreas may be quite atrophied making it difficult to visualize and identify. Unfortunately, if this important tissue is missed, the diagnosis may be lost.
Any marmoset or tamarin suffering from chronic diarrhea and weight loss should have appropriate diagnostic tests performed, including complete blood count, chemistry profile, radiographs, fecal flotation and direct smear, ultrasound, or other appropriate diagnostics. Consider sending feces preserved in 2% formalin to PRL, Inc. for thorough examination. Since eggs are only sporadically shed in the feces, it is likely that the diagnosis can be missed antemortem.8 Callitrichids suffering from wasting usually show very low blood calcium levels, low total protein, and varying white blood cell count levels in this author's experience.
Treatment should be instituted if signs of wasting occur, including good support care, providing an easily digestible diet, oral or parenteral fluid administration, and administering fenbendazole (Panacur, 10% paste, Hoechst Roussel Vet, Warren, NJ, USA) at 100 mg/kg P0 q24h for 14 days (Cathy Johnson-Delaney, oral communication, February 1997). This is easily administered by using the equine paste on a marshmallow, which is readily consumed. Prophylactic deworming periodically is a good idea if callitrichids have any chance of consuming cockroaches, since pancreatic worm eggs are infrequently passed in the stool.3
Callitrichids with chronic diarrhea often crave protein. This author recommends offering plenty of cooked meat, cheese, scrambled egg), and other favored items. Chicken sticks (Gerber Products Co) may be offered on occasion, as the onion powder should not be as great a concern in adult callitrichids. They also seem to crave calcium (which may correspond with the hypocalcemia often seen). Offer chewable antacid tablets ad libitum (calcium carbonate 500 mg, Chewable Antacid, Regular Strength, Dayton Hudson Corp, Minneapolis, MN, USA). Give parenteral fluids as needed. Use broad-spectrum antibiotics to treat any associated bacterial infections and anti-diarrheal medications. Supply a sick callitrichid with heat, as most require supplemental heat when ill. A heating pad set on low, covered with a towel, works well. While many callitrichids with chronic diarrhea and weight loss may not recover, it is possible to return some to good health. Diligent support care and proper medications to control diarrhea may turn around an ill animal. One that has recovered from chronic diarrhea and weight loss may relapse, so it must be closely observed and aggressively treated if the diarrhea recurs. It has been noted by this author that consumption of mealworms may cause diarrhea that spontaneously resolves.
Bacterial infections: Infection with Streptococcus zooepidemicus septicemia may occur.5 Yersinia enterocolitica and Y. pseudotuberculosis may occur.5 This author has seen sporadic infection caused by a sick squirrel that crawled over callitrichid cages, contaminating the environment. Peracute death occurred and hepatic lesions were the most common lesions seen on gross necropsy. The livers were mottled with white suppurative foci containing massive colonies of Y. enterocolitica. Pasteurella, Klebsiella and Bordetella may also cause disease.5 Tularemia has been reported in callitrichids. Campylobacter, Pasteurella, Shigella, Aeromonas hydrophilia, Salmonella and enteroadherent Escherichia coli can cause disease. Bite wounds may be contaminated with several different species of bacteria. Other bacteria may also occasionally cause disease in callitrichids.
Hemosiderosis: Accumulation of iron pigment in the liver has been observed in neonatal and adult callitrichids. Iron metabolism is not well understood in callitrichids. It may be wise to use a baby formula low in iron to reduce the risk of hemosiderosis. Foods high in iron should also be restricted. Fruit and vitamin C enhance gut absorption of iron, so these should be fed judiciously to callitrichids.5 Vitamin C is however, necessary in the diet of callitrichids, so a balance must be achieved. Because they do like sweet foods and fruits, fruit should be limited in the diet. Fruit also usually contains an improper calcium:phosphorus ratio, which can also be problematic. This author has only had hemosiderosis diagnosed in 2 callitrichids out of 52 that have had complete histopathological examination of tissues. This condition may be related to management, diet and husbandry conditions in the collection or individual environment.
Tail alopecia: Alopecia at the base of the tail may have many causes. Nutritional deficiencies may present as alopecia of the tail. Callitrichids with pancreatic worms may also develop tail alopecia. It may also occur as a result of overgrooming, excessive scent marking, or (rarely) dermatophytosis or bacterial dermatitis.
Colitis, colon cancer, and tumors: Chronic colitis is commonly encountered, especially in geriatric callitrichids. Cotton-topped tamarins are known to develop colon cancer that is similar to that occurring in humans. These tamarins were used in laboratories as a model for this cancer in humans, until they went on IS, Appendix One. Diet may play a part in colon cancer and chronic colitis. Occasionally, other types of tumors may occur in callitrichids.
Coprophagy: This is occasionally observed in callitrichids. This may be the result of dietary deficiencies or of severely limited protein in the diet.8 Coprophagy is not usually the result of boredom, and it may be dangerous because it may spread bacteria and protozoa to the family group. Using a grate in the bottom of the cage will somewhat limit coprophagy by preventing access to fecal material.
Viral diseases: Two important viruses in callitrichids are lymphocytic choriomeningitis (LCM) caused by an arenavirus and encephalomyocarditis. The rat and mouse are the host reservoirs for LCM, which causes anemia and hepatitis in affected monkeys. LCM may be seen in callitrichids kept in cities, apartment buildings, or other areas where callitrichids might have access to mice and rats or their excretions. Transmission is by aerosol route.10 LCM is also referred to as callitrichid hepatitis. LCM is a zoonotic disease however many humans already have a protective titer against LCM (Col. Nancy Jaax, June 1999). Callitrichids should never be fed pinky mice due to the risk of transmission of LCM.5 Strict rodent and insect control is vital to prevent the transmission of many dangerous diseases to callitrichids. Encephalomyocarditis may occur most frequently in zoos and also had a suspected host of rats and mice.5 Other viruses may be transmitted to callitrichids from other nonhuman primates or humans. Coronaviruses and adenovirus have been isolated and are of questionable pathogenicity.5
Callitrichids are susceptible to Eastern Equine Encephalitis and the other equine encephalitis viruses. It is suspected that they are also susceptible to the West Nile Encephalitis virus (oral communication, Col. Nancy Jaax, July 2000). They are susceptible to hepadenoviruses and other hepatotropic viral diseases. In lab setting, inclusion body hepatitis, parainfluenza type 1 (Sendai) and a paramyxovirus distinct from measles has been reported.5
Parasitology: Toxoplasmosis occurs sporadically in callitrichids. Giardia may cause diarrhea and malabsorption. Spirurid nematodes and thorny-headed worms, Prosthenorchis elegans can affect marmosets and tamarins, and are carried by cockroaches and coprophageous beetles. Surgery is required to remove thorny-headed worms. Pancreatic worms can cause chronic malabsorption and wasting and may be very difficult to diagnose antemortem. Human pinworms, Enterobius vermicularis, may infest callitrichids, and conversely, it is thought that pinworms infesting nonhuman primates (Enterobius species) may infest humans.11 Pinworms, while usually not pathogenic, may cause serious enteritis by invasion of the intestinal wall, and they may even result in fatal infestation. The raccoon roundworm, Baylisascaris procyonis, may cause cerebrospinal nematodiasis (larval migrans). The oral spirurid, Gongylonema pulchrum, may occur in Goeldi's monkeys and pygmy marmosets. Treatment with fenbendazole (Hoechst Roussel Vet) at 40-60 mg/kg PO for 5 consecutive days may be attempted.5 Oral spirurids and pancreatic worms are more difficult to eradicate. Golden lion tamarins may have significant problems with the spirurid nematode Pterygodermatites nycticebi.5
Toxin exposure: Lead poisoning may occur in tamarins and marmosets kept in apartments and houses painted with lead-based paint. Other toxicoses are not common in callitrichids, but due to their inquisitive nature, they may ingest pills meant for the owners or other housepets. They seem particularly fascinated by pills ingested by humans, and they may try to snatch them away from unsuspecting owners, or they may remove pills from blister packs or bottles, if they can.
Nutritional secondary hyperparathyroidism: Metabolic bone disease (MBD) or rickets may occur in babies weaned too early, and especially in those living indoors, that are not exposed to ultraviolet light. MBD also occurs in older callitrichids fed improperly and housed indoors. Infants of females with inadequate vitamin D3 levels may be more susceptible, as well. Calcitonin-salmon (Calcimar, Rhone-Poulenc Rorer Pharmaceuticals, Collegeville, PA, USA) has proved to be a remarkable drug for the treatment of MBD in the hands of this author. Diagnostics and treatment as for other species with MBD should be instituted. The dosage of calcitonin-salmon (Rhone-Poulenc Rorer Pharmaceuticals), once the callitrichid has been pre-treated with injectable and oral calcium supplementation, is 2 U SC for a small marmoset or tamarin weighing less than 100 g; 4 U for a callitrichid weighing between 100-250 g; and as much as 6 U for callitrichids weighing more than 250 g. These doses are empirical, but have worked well for this author. During the first week it is given q48h, and during the second week it is given q72h, and by the third week it is administered twice weekly or once weekly. Weekly injections should be continued until the animal is acting normally and is ambulating well.3
Urinary tract disease: Bacterial cystitis may occur. Callitrichids have a relatively high incidence of glomerulonephropathies.5 Renal disease in pygmy marmosets resembles forms of hypertensive nephropathy associated with vascular lesions.5
Cardiac disease: Disease associated with hypertension in pygmy marmosets has been described. This occurs most often in obese pygmy marmosets that are offered high fat/high cholesterol diets.
Dystocia: Dystocia may require that a C-section be performed. If radiographs indicate a baby may pass through the pelvis, oxytocin (Syntocinon, Sandoz Pharmaceutical Corp., East Hanover, NJ, USA) may be given. Relatively high doses of oxytocin (Sandoz) may be necessary to cause effective uterine contractions. It is dangerous to delay surgery. Females usually go into labor after sunset and successful delivery will occur quickly. The entire birth process usually takes less than 1 hour. If a female in labor is not discovered until morning, chances are that the babies are already dead. Medical treatment may be attempted, but if unsuccessful, surgery should be performed as soon as the female is stabilized. Oxytocin therapy may be attempted, once parenteral calcium, fluids, vitamin D3, and antibiotics have been administered. An empirical protocol this author has used for uterine inertia is: 0.15 U IM, initially, followed by IM injections q 20 min, increasing the dosage to 0.2 U, 0.5 U, 1.0 U, and 2 U. To accurately dose small amounts, one can dilute the oxytocin with lactated Ringer's solution.3
If unsure as to whether or not a female has ruptured the amniotic sac, take a sterile cotton-tipped applicator moistened with sterile saline and gently swab the vaginal canal. Roll the collected liquid onto a glass slide and examine under the microscope. Dried amniotic fluid appears as ferning on the slide and appears rainbow-hued.3 If the amniotic sac has ruptured it is more likely that the female may require emergency surgery. This technique may help the clinician in deciding which course of action should be taken (surgery or medical management).
It may be valuable to consult with a human obstetrician/gynecologist for advice, as delivery is very similar to that of humans. Isoflurane (Baxter Pharmaceuticals) may be used in a C-section, after a pre-anesthetic dose of atropine at 0.2 mg/kg SQ (Atropine Sulfate Injection, Baxter Pharmaceuticals, New Providence, NJ, USA) is administered. Remember that monkeys have nimble hands and teeth, and they often remove sutures post-op. Consider using stainless steel sutures, or using an encircling abdominal bandage post-operatively (for 7-10 days). The female may need to be separated from her family group as other family members may try to remove sutures during grooming. This must be weighed against the stress of isolation from the family group. Pain management post-operatively should be provided. This author administers acetaminophen and hydrocodone syrup (Lortab Elixir, 7.5/500 mg per 15 ml, UCB Pharma, Inc, Smyrna, GA, USA) at a dose of 0.22 mg/kg (of the hydrocodone portion) PO q8h to q12h for several days after surgery. This elixir is palatable and will usually be taken without difficulty. Butorphanol tartrate (Torbutol, 0.5 mg/ml, Fort Dodge Laboratories, Inc, Fort Dodge, IA, USA) dosed at 0.4 mg/kg SC q12h to q8h PRN can also be used.
A federal permit or license is not needed to own a marmoset or tamarin; however, a United States Department of Agriculture (USDA) license is required to breed, exhibit, or sell one. A prospective owner should inquire to ensure that the breeder or dealer selling monkeys has the necessary license. Disreputable dealers and brokers will sell primates to capitalize on profit opportunities. Anyone selling nonhuman primates without a license should be immediately reported to the USDA. County or state agencies may require permits or licenses in order to possess nonhuman primates, and some local, county, and state laws may prohibit private individuals from owning them. In order to transport callitrichids for sale across state lines, for IS, Appendix One: Callitrichids, it is necessary for one to possess a Federal Fish and Wildlife Permit, issued by the Department of the Interior, US Fish and Wildlife Service. This is commonly called a CBW (Captive Bred Wildlife) permit.
Marmosets and tamarins are beautiful, intelligent monkeys. Even so, unless a family has owned monkeys before, they should be discouraged from purchasing a callitrichid as a pet. Even with past experience, such a decision should not be undertaken lightly. If a client has decided to purchase a monkey, suggest that they consider purchasing an unrelated pair and eventually breed them. That way they can enjoy the infants and juveniles, and when the monkeys outgrow their cuteness, they can contribute to conservation efforts.
Copyright © 2006 Margaret A. Wissman, D.V.M., D.A.B.V.P.
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