Exotic and Laboratory Animals

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 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.

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.

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.

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 years. 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 and/or veterinary care.

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 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.

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).

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 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 (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.

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. Prosimians such as Lemur catta (ring-tailed lemur) and New World monkeys such as Cebus albifrons (white-fronted capuchin) are commonly encountered in zoological and private practice.

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 (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.

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.

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.

The class Reptilia includes >10,000 species, but only a few dozen are likely to be encountered in general practice. All the Crocodilia, front-fanged venomous snakes (but not all rear-fanged venomous species) and both species of venomous 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 in detail here. The class Reptilia includes four orders: Crocodyla (crocodiles, alligators, gharials), Testudines (turtles and tortoises), Squamata (lizards and snakes), and Rhynchocephalia (tuatara).

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 sliders are small, nocturnal marsupials native to Australia, Indonesia, and New Guinea that have become popular pets. Their name derives from the thin membrane of tissue (the patagium) that extends from the wrists on their forelimbs to their ankles on their hindlimbs that allows them to glide from tree to tree in the wild. Wild sugar gliders live in large social groups and fare better in captivity when housed in pairs. They are omnivorous hindgut fermenters that rely on bacterial cecal fermentation to digest carbohydrates. In the wild they eat a variety of plants, sap, and invertebrates. This diet is hard to mimic in captivity, predisposing captive gliders to nutrient deficiencies and disease.

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.

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.

Vaccination is used in exotic mammals to prevent diseases just as it is in domestic animals; however, vaccination is often extralabel, and the protocols are often based on closely related domestic species and limited publications. Few efficacy or challenge studies exist, and protection is generally assumed based on serologic titers, which may be unreliable in documenting true protection. Modified live vaccines (MLV) are used with caution in certain species due to well-documented reports of virulence in these species. Core vaccines to protect against major infectious diseases are used in captive exotic mammals. Exotic mammals may also be vaccinated to protect vulnerable wild populations against life-threatening, globally distributed diseases.