Exotic and Laboratory Animals

Amphibians

The class Amphibia is composed of three orders: Anura (frogs and toads), the largest with >3,500 species; Caudata (salamanders, newts, and sirens) with ~375 species; and Gymnophiona (caecilians) with ~160 species.

Aquaculture

Aquaculture is the production of marine and freshwater organisms under controlled conditions. Hundreds of different species of aquatic animals are raised in aquaculture and include fish and aquatic invertebrates cultured for food, the aquarium hobby, bait, recreational fisheries, research, private ponds, and stock enhancement of wild populations. Animal aquaculture was valued at $137.7 billion (USD) worldwide in 2012, with China’s production valued at $66 billion and the USA’s at $1 billion. Within the USA, major commercial commodities include channel catfish, centered around the Mississippi Delta; rainbow trout in the north/northwest, including Hagerman Valley, Idaho; Atlantic salmon in the Pacific northwest and Atlantic northeast; aquarium fish with production centered in Florida; baitfish in Arkansas; and goldfish and koi production scattered throughout the USA. In addition, other public and private entities, including research facilities, public aquaria, and hobbyists, are breeding numerous other species.

Aquarium Fishes

Aquatic medicine has emerged as a recognized specialty within the practice of zoologic medicine. Fish medicine, an important component of the aquatic specialty, is evolving, with distinct subspecialties of aquaculture and production medicine (see Aquaculture) as well as pet and exhibit fish medicine that focuses on individual animals. This chapter focuses on pet and exhibit fish medicine.

Aquatic Systems

A fundamental assessment in working with aquatic species is examination and evaluation of the life support system sustaining the animals. This is a critical step in the clinical examination of any aquatic species, not just fish. The emphasis of this chapter is on aquarium and aquaculture systems, but the principles may be applied to life-support designs for all aquatic organisms.

Backyard Poultry

Raising backyard poultry (Gallus domesticus) in urban environments is a growing trend in the USA. In developing countries, backyard poultry represent ~80% of poultry stock, often consisting of indigenous unselected breeds of various ages, with various species mixed in the same flock. This serves to meet household food demands and is an additional source of income. Modern day USA backyard poultry owners often view their birds as companion animals, in contrast to poultry raised for commercial production. A 2010 USDA study in four cities (Los Angeles, Denver, Miami, New York) found that 0.8% of all households owned chickens, and nearly 4% of households without chickens planned to have chickens in the next 5 yr. As backyard poultry ownership becomes increasingly popular, owners must be properly educated about how to keep their flocks healthy; thus, more veterinarians must be capable of providing this education.

Ferrets

The domestic ferret (Mustela putorius furo) is in the order Carnivora, family Mustelidae, and has been in captivity for more than 2,000 years. Ferrets are used as research animals, often in studies of the respiratory system and as a model for Helicobacter sp infection. They have become popular pets in recent years in the USA. They are also used as hunting animals in Europe, Australia, and New Zealand.

Hedgehogs

Hedgehogs are in the family Erinaceidae, within the order Insectivora. The central African hedgehog (Atelerix albiventris), also known as the white-bellied, four-toed, or African pygmy hedgehog, is native to dry, open habitats in central and eastern Africa. They are nocturnal and very active, jogging for miles in search of invertebrate prey. In the USA, it is illegal to own a hedgehog as a pet in some states and municipalities; in other states, a permit is required. Additionally, a USDA permit is required to breed, transport, sell, or exhibit hedgehogs.

Laboratory Animals

Most American laboratories must adhere to two main sets of animal welfare regulations: the Animal Welfare Act (AWA; created in 1966) and the Public Health Service Policy on Humane Care and Use of Laboratory Animals (PHS Policy; originally enacted in 1985).

Llamas and Alpacas

The four members of the South American camelids (SACs) are the llama, alpaca, guanaco, and vicuña. Although their progenitors originated in North America,these species evolved in the South American Andes, with the wild guanaco and vicuña serving as the foundation stock for the domesticated llama and alpaca, respectively.

Marine Mammals

Marine mammals are a diverse group of species that include cetaceans, pinnipeds, sirenians, sea otters, and polar bears. The cetaceans consist of two major groups with different physiology and anatomy: toothed whales (Odontocetes) and baleen whales (Mysticetes). The pinnipeds consist of three major groups: true seals (Phocidae), eared seals (Otariidae), and walruses (Odobenidae). Sirenians (Sirenidae) are of a single family that includes manatees and dugongs. The sea otter (Enhydra lutris) is a marine member of the Mustelidae, and the polar bear (Ursus maritimus) is the only member of the Ursidae that is considered marine.

Mink

Mink (Mustela vison) are housed individually in raised, wire mesh pens. A nest box with a hole for entry is attached outside or placed within the pen. Wood used for the nest box should not be painted or treated with wood preservatives. Soft, awn-free marsh hay, clean straw, untreated dry wood shavings, or fine wood-wool make suitable nest material. Nest boxes should be cleaned and nest material replaced as required, especially before whelping. Sheds are used throughout the year and should admit natural daylight. There should be plenty of air circulation and shade in the warmer months.

Nonhuman Primates

This overview presents a working knowledge of the common families of nonhuman primates maintained in captivity. More species than ever are now promulgated and maintained in captivity, and many are kept in private facilities. Prosimians such as Lemur catta (ring-tailed lemur) and New World monkeys such as Cebus albifrons (white-fronted capuchin) are commonly encountered in practice. The nonhuman primate species most widely used in research are the macaques, Macaca mulatta (rhesus monkey), M fascicularis (cynomolgus monkey), and M nemestrina (pig-tailed monkey); some African species, primarily Chlorocebus aethiops (African green monkey, vervet) and Papio spp (baboons); and some of South American origin, Saimiri sciureus (squirrel monkey) and Aotus trivirgatus (owl monkey). Saguinus spp (marmosets) and Callithrix spp (tamarins, marmosets), also of South American origin, have had more limited use in research but are common in the pet trade.

Pet Birds

Advances in avian medicine have changed the emphasis from infectious diseases and emergency medicine to wellness care. Nutrition and behavior are important components of the health of psittacine birds and play a major role in pet bird wellness programs. Mass importation of wild-caught psittacine birds was curtailed in the mid-1980s, and the current pet bird population is comprised primarily of captive-bred parrots. This has resulted in novel medical concerns and unique behavioral challenges. The knowledge base regarding psittacine and other pet bird diets and husbandry continues to increase, as does the importance of providing a psychologically suitable environment for these complex animals. Pet birds are intelligent and social animals adapted for flight. Keeping solitary pet birds in small indoor cages, with limited opportunity for exercise, has both physical and psychological consequences.

Potbellied Pigs

Potbellied pigs (PBPs) have a short to medium wrinkled snout, small erect ears, large jowls in proportion to the head, short neck, pronounced potbelly, swayed back, and straight tail with a switch at the end. The CON and LEA lines of PBPs at 1 yr of age should not be >18 in. at the withers (ideal height ≤14 in.) or weigh > 95 lb (ideal weight ≤ 50 lb). The life span of PBPs is probably 8–20 yr with ~10–15 yr typical. Very small or obese PBPs may have a shortened life span. For hematologic and serum biochemical reference ranges, see Table: Hematologic Reference Ranges and see Table: Serum Biochemical Reference Ranges.

Rabbits

The European or Old World rabbit (Oryctolagus cuniculus) is the only genus of domestic rabbits. Wild rabbits and hares include cottontail rabbits (Sylvilagus) and the “true” hares or jackrabbits (Lepus). Rabbits have been bred for fur, meat, wool, exhibition, and for use as laboratory animals. The closest relative to the rabbit is the pika (Ochotona princeps), which lives in cold climates such as the Rocky Mountains. Rabbits are not rodents.

Ratites

Twelve species of birds are grouped as ratites, not including the order Tinamiformes. These include the ostrich, emu, rhea, cassowary, and kiwi. The ostrich, emu, and rhea are the ratite species primarily raised in production facilities, whereas all may be found in zoo collections. The ostrich originated in Africa and has been commercially raised since 1850 for feathers, meat, and hide products. The emu is native to Australia and has been raised for meat, oil, and leather in many countries around the world, including the USA. The South American rhea has been produced primarily for feathers.

Reptiles

The class Reptilia includes >8,000 species, but only a few dozen are likely to be encountered in general practice. All the Crocodilia, front-fanged poisonous snakes (but not all backed-fanged poisonous species) and both species of poisonous lizard (Heloderma spp) are considered to be dangerous animals and are usually covered by federal and/or state legislation. These species are not generally kept as pets and will therefore not be discussed here. The class Reptilia includes four orders: Crocodyla (crocodiles, alligators, gharials), Testudines (turtles and tortoises), Squamata (lizards and snakes), and Rhynchocephalia (tuataras).

Rodents

The order Rodentia, with ~2,020 living species placed in 28 families (approximately half of all mammalian species), is the largest order of mammals. They are found worldwide except in Antarctica and on some oceanic islands. Ecologically, they are remarkably diverse. Some species spend their entire lives above the ground in the canopy of rainforests; others rarely emerge from beneath the ground. Some species are aquatic, whereas others are equally specialized for life in deserts. Many rodents are to some degree omnivorous; others are highly specialized, eating, for example, only a few species of invertebrates or fungi.

Sugar Gliders

Sugar gliders (Petaurus breviceps) are small, nocturnal marsupials native to Australia, Indonesia, and New Guinea that live in eucalyptus and acacia forests. They belong to the family Petauridae, which includes the wrist-winged gliders. Gliders in this family possess a gliding membrane (patagium) that runs from the wrist of the forelimb to the ankle of the hindlimb and that allows them to glide as far as 50 m and forage for food using less energy. They use their tails as stabilizing rudders that enable them to change direction easily. The second and third toes on their hindfeet are fused to form a "grooming comb" that helps them clean their fur. Females are seasonally polyestrous and have a double vagina, two uteri, and a pouch containing four teats; they often have twin births. After 16 days of gestation, the young (joeys), each weighing only 0.2 g, migrate to the pouch to develop further and finally leave the pouch after 70–74 days. They remain in the nest until 110–120 days of age, when they are weaned. They stay with the colony until 7–10 mo old. Males have a forked penis (to match the female's double vagina) and a pendulous scrotum containing two testicles. Males do not urinate from the forked end of the penis but from the proximal end. Both males and females have paracloacal scent glands adjacent to the vent (the cloacal opening or common opening of urinary, reproductive, and GI tracts) with which they mark territory and each other, and males also have frontal scent glands on their foreheads and glands on their throats and chests. Sparse fur and an oily discharge are normal on the frontal and sternal glands of postpubescent males. These glands give both sexes a musky odor.

Tasmanian Devils

The Tasmanian devil is the largest marsupial carnivore in existence, currently restricted to the island-state of Tasmania, Australia. Devils have black fur, and white flashes on the chest and rump may be present. They are sexually dimorphic, with males having a thicker neck and broader head than females. Males typically weigh 9–12 kg (up to 14 kg), and females 6–8 kg (up to 9 kg). Devils are mainly nocturnal and hide during the day in rock dens, log cavities, or underground burrows made by other animals. They live up to 6 yr in the wild and 9 yr in captivity. Devils are nonterritorial and generally live within an area of 10 km². They can occupy a wide range of habitats, from dry sclerophyll forest, open eucalypt environment, and coastal woodland, to pasture and agricultural areas where carrion (from domestic livestock and macropod populations) is abundant. Devils are specialist carrion feeders but will hunt prey, particularly those weakened by disease, injury, or old age. Wallabies, wombats, and sheep are the usual source of carrion, but other dead domestic livestock, roadkill, and 1080-poisoned wildlife are also consumed. The proportion of hunting to scavenging is unknown. Female devils are facultative polyestrus with up to three estrous cycles within a breeding season, each cycle ~60 days apart. They are polyovular (up to 114 oocytes per ovulation) and may give birth to up to 40 embryos. Mating peaks over late February to the end of March and, as is typical for marsupials, females give birth to highly undeveloped young ~3 wk after mating. Females have a rear-facing pouch, with four teats in the pouch cavity, limiting the maximum total offspring raised per year to four. The young are carried in the pouch until they are 4–5 mo old, weaned at 5–8 mo, and become independent at 10–12 mo. Sexual maturity is reached at 2 yr of age for both females and males, although females have been confirmed to reproduce as young as 1 yr old.

Vaccination of Exotic Mammals

Exotic mammals are susceptible to many of the same infectious diseases that affect domestic mammals. However, vaccination of these species is often extra-label, because vaccines are tested and approved for use only in domestic species. Vaccination protocols recommended for exotic mammals are therefore based on limited published information, anecdotal experience, and relative risk of disease to the species from the infectious agent or vaccination itself. Reports of lack of seroconversion, antibody production, sustained protection, and induction of the disease resulting in morbidity and mortality in a variety of species, particularly for rabies and distemper, are common after vaccination of exotic mammals. Regardless, vaccination should be considered in captive wildlife and conservation programs based on a number of factors. Many diseases preventable by vaccination such as canine distemper virus, canine parvovirus, feline calicivirus, feline panleukopenia virus, and rabies virus have caused population declines or reduced host fitness in critically endangered mammals. Certainly, infectious disease outbreaks in small numbers of highly genetically valuable individuals can disastrously affect conservation projects. Unfortunately, the biology of many of these preventable diseases (incubation period, transmissibility, etc) in exotic mammals is often unknown. Captivity may enhance the risk of acquiring disease based on food sources, exposure to rodents and other disease hosts, and an unknown degree of exposure of other zoo animals, which is unlikely to occur in nature. Thus, due consideration of protection of captive nondomestic species, even those destined for release to the wild, is warranted. Core vaccines are designated as those that protect captive animals from life-threatening, globally distributed diseases. The determination of protection has largely been based on studies in domestic species; nonetheless, based on current knowledge, these vaccines deserve full consideration for inclusion into vaccination regimens for captive exotic mammals.

Zoo Animals

The physical health as well as the social and behavioral well-being of zoo animals depends on enclosure design, nutrition, husbandry, management, group social structure, behavioral enrichment, and good medical and surgical care. Naturalistic enclosures with soil and vegetation are appealing to the public and more stimulating for the animals, but they present challenges for both sanitation and parasite control programs and may complicate restraint procedures. Mixed species exhibits may increase risk of disease transmission between species and can result in interspecific aggression if appropriate choices are not made.

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