The class Amphibia has >7500 described species, including 3 orders: Anura (Salientia), Caudata (Urodela), and Gymnophiona (Apoda). Anura refers to tailless amphibians and is the largest order, comprising >6000 species, including frogs and toads (. Caudata refers to amphibians with tails (salamanders, newts, and sirens) and comprises >700 species (). The order Gymnophiona is made up of >100 species of caecilians. Caecilians are wormlike amphibians that inhabit both aquatic and terrestrial environments. They are rarely kept in the care of humans. Amphibian populations are declining due to a complex mix of factors including habitat loss, climate change, infectious disease outbreaks, toxin exposure, and pollution.
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 $231.6 billion (USD) worldwide in 2016. China is currently the largest producer, accounting for approximately 61.5% of the world total tonnage of food fish. By contrast, North America (including the US) accounts for approximately 0.8%. Within the US, 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 US. 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 zoological medicine. Fish medicine, an important component of the aquatic specialty, is evolving, with distinct subspecialties of aquaculture and production medicine 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 lived in captivity for >2,000 years. Initially primarily used for hunting, ferrets are now common pets worldwide. They are also used as research animals, often in studies of the respiratory system, in particular influenza virus infections, and as a model for Helicobacter sp infection.
Hedgehogs are solitary, nocturnal mammals in the family Erinaceidae, order Eulipotyphla, which includes shrews and moles. The African pygmy hedgehog (Atelerix albiventris), also known as the white-bellied, four-toed, or central African hedgehog, is native to dry, open habitats in central and eastern Africa. Hedgehogs are nocturnal and very active, traveling for miles in search of prey. In the US, some states and municipalities require a permit to keep a hedgehog as a pet; in some parts of the US it is illegal. 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; Public Law (PL) 89-544 of 1966), with the associated Animal Welfare Act Regulations (AWAR) defining standards and requirements, and the Health Research Extension Act of 1985 (PL 99-158), which provides the legislative mandate for the Public Health Service Policy on Humane Care and Use of Laboratory Animals (PHS Policy).
The domesticated llama (Lama glama) and alpaca (Vicugna pacos) are the best known South American camelids (or New World camelids, as distinguished from their Old World relatives camels). As a family, the Camelidae actually originated in the North American continent, migrating outward. The guanaco (Lama guanicoe) and vicuña (Vicugna vicugna)—wild counterparts of the llama and alpaca—face major conservation threats. Of the camelid species, the vicuña population is the smallest. The vicuña lives in Peru and Argentina, typically at high elevations and often in tundra marshes. The vicuña has an extraordinary luxury fiber coat, softer than cashmere and finer than silk, and has been overhunted to near-extinction despite being protected throughout most of South America. Guanaco inhabit a large range in South America, from northern Peru to southern Chile, and prefer semi-arid shrub and grasslands. Guanaco face overhunting and loss of habitat.
Nutritional muscle degeneration and steatitis ( yellow fat disease) may occur in large, rapidly growing male mink as a result of feeding rancid or excessive, unsaturated fatty acids, together with a deficiency of vitamin E or selenium in the diet. Morbidity and mortality are variable on farms; however, without treatment, mortality may be up to 75%. Affected mink may be found dead, or they may exhibit mild hind end ataxia followed by death. Postmortem findings include serosanguinous effusion within the pericardial sac or thorax, red or white epicardial streaks (similar to white muscle disease in other species), dark urine in the bladder (due to myoglobinuria), and sometimes yellow, edematous internal or subcutaneous fat.
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, and .
The European or Old World rab`bit (Oryctolagus cuniculus) is the only genus of domestic rabbits. Wild rabbits and hares include cottontail rabbits (Sylvilagus spp) and the “true” hares or jackrabbits (Lepus spp). Rabbits have been bred for fur, meat, wool, exhibition (shows), and for use as laboratory animals. The closest relative to the rabbit is the pika (Ochotona spp), are two species which live in mountainous areas in Asia and in North America. Rabbits are classified as lagomorphs, not rodents.
Twelve species of birds are grouped as ratites, not including the order Tinamiformes. These species include the ostrich, emu, rhea, cassowary, and kiwi. The ostrich, emu, and rhea are the ratite species primarily raised in production facilities, whereas all ratite species may be found in zoo collections.
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.
Medical care of zoo animals has become more holistic over the past decade, encompassing all aspects of animal welfare by incorporating attention to the social and behavioral well-being of the animals, in addition to their physical health. Such a comprehensive approach to healthcare considers enclosure design, nutrition, husbandry, management, group social structure, behavioral enrichment, and good medical and surgical care.
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.