Although exotic mammals and birds are susceptible to many of the diseases that affect their domestic counterparts, they are rarely presented to veterinarians in sufficient numbers to justify the development of specific vaccines for each species. Mink, foxes, and rabbits raised commercially for their fur and meat respectively are exceptions. As a result, it is usual to vaccinate exotics “extra-label.” Should a veterinarian use a vaccine in a species not specified on the label or on the package insert, they must assume full responsibility for product failure or any adverse consequences. Vaccines developed and considered safe for a specific domestic species may not be safe or efficacious in related wild species. However, captivity may expose animals to a greater risk of contact with pets or livestock, and exposure to pathogens, compared with their free-living counterparts. In many cases, there is a significant lack of information on diseases in exotic species. Before considering vaccination of exotic pets, the veterinarian must ensure that the owner is legally in possession of the animal because in many jurisdictions, ownership of certain species is restricted. As always, informed consent is critical considering the lack of hard data regarding the use of vaccines in these species. Constraints on new vaccine production and marketing include the cost and complexity of production, in addition to the relatively small size of the market for exotic species. The relative complexity of many new vaccines, and expensive and complex licensing requirements are reflected in vaccine cost. A serious expense gap exists between our ability to make sophisticated vaccines in a laboratory setting and to manufacture and market these products at a reasonable price. Manufacturers are therefore reluctant to make a large investment in new vaccine production for less abundant species. Vaccination of free-living species presents totally different considerations. Because wildlife vaccination is primarily undertaken by, and often restricted to, government agencies either for public health reasons such as rabies or plague control, for conservation reasons as in saving an endangered population, or for population control purposes, no commercial market for wildlife vaccination exists. Modified live vaccines pose a health risk to exotic mammals and may not be effective. Vaccines attenuated for domestic mammals such as dogs and cats may retain significant virulence for wild mammals. The bacterium, Erysipelothrix rhusiopathiae, is pathogenic for peccaries, nondomestic pigs, cetaceans, and pinnipeds. An erysipelas bacterin can be administered by a standard protocol to nondomestic pigs (including pot-bellied pigs) and peccaries. Some dolphins may be healthy carriers of this organism. Erysipelas bacterins are not widely used in captive cetaceans because of the risks involved in immobilization, and the prevalence of adverse reactions, especially hypersensitivities leading to death. Vaccination is not recommended for pinnipeds. Leptospirosis occurs sporadically in many different mammals. Although vaccination with a Leptospira bacterin is considered noncore in dogs, vaccination should be considered when exotic species are housed in an endemic area, or if this disease is known to be a problem in the collection. Selection of serovars depends upon those known to be present in a region. However, serovars Canicola and Icterohaemorrhagiae should be included in any vaccine. Carnivores should be vaccinated at six to eight weeks of age, boosted two weeks later, and revaccinated every six months. Ruminants, pigs, and peccaries should receive the 5-way bacterins including Pomona, Hardjo, Icterohaemorrhagiae, Canicola, and Grippotyphosa. Because the available bacterins are poorly immunogenic, semiannual vaccination is probably necessary to maintain immunity. Many exotic species are susceptible to clostridial diseases, especially tetanus. These include equids, elephants, great apes, deer, camelids, and also sheep and goats. The equids and elephants should be vaccinated on the same schedule as domestic horses with primary immunization at three to four months, a second dose one month later and annual revaccination. Ruminants including deer, antelope, and camelids should receive 8-way combined clostridial bacterins. Other domestic hoof stock should receive tetanus toxoid according to the manufacturer’s recommendations. Pot-bellied pigs should be vaccinated against tetanus. Primates should receive human tetanus toxoid. Two intramuscular doses given at an interval of 4 to 5 weeks followed by revaccination 6 to 12 months later, and subsequent boosting every 3 to 5 years or after an injury. Exotic sheep, goats, llamas, and alpacas should receive the core sheep vaccines, especially Clostridium perfringens toxoids C and D and other clostridial vaccines as required in addition to tetanus (Chapter 17) (Box 20.1). Clostridium botulinum has caused lethal disease in many different mammals especially mink. Botulism type C toxoids for mink have been available for many years. As described in Chapter 16, there are numerous vaccines available to protect domestic cattle against rhinotracheitis caused by bovine herpesvirus 1. It would be safer to use inactivated vaccines in exotic hoof stock in view of the known hazards of the modified live vaccines. The same applies to bovine virus diarrhea vaccines. Sheep and goats are susceptible to respiratory disease caused by Mannheimia haemolytica and parainfluenza 3. Modified live vaccines are available for domestic sheep and goats. Intranasal vaccines should be administered as directed on the label for domestic species with annual boosting. Most of the Carnivora including canids, hyenas and aardwolves, procyonids, mustelids, especially mink and otters, viverrids, and both giant and red pandas are susceptible to distemper. Large felids such as lions, leopards, and tigers (Panthera spp.) are also susceptible to canine distemper virus (CDV) so that this should be considered a core vaccine in these species, although its efficacy is unclear. The risk of distemper in small felids appears to be low, but lethal distemper has been reported in lynx. Recent molecular evidence suggests that CDV isolates from large felids are distinctly different from current vaccine strains. Xenarthra such as sloths are also susceptible to distemper. However, there is some debate as to the best canine distemper vaccine to use in these exotic species. One of the major issues with vaccinating exotic species is a history of modified live virus (MLV) vaccines causing lethal distemper in nondomestic species. The newer canarypox-vectored subunit distemper vaccines appear to be safe and usually effective, although they may not stimulate as strong an antibody response as traditional MLVs. It is suggested that the first vaccine dose should be given to canid pups when maternal antibodies wane around 6 to 9 weeks, followed by boosters every 2 to 3 weeks until 16 to 20 weeks, followed by annual revaccination. The persistence of maternal antibodies also varies among species so current recommendations suggest that the final dose should be given at 18 to 20 weeks in raccoons, and after 10 weeks in ferrets. The duration of immunity following vaccination in these species is unclear. For some, such as red foxes, immunity lasts about 3 years, but data is lacking for others. A common distemper virus strain used in modified live CDV vaccines is Snyder Hill. This strain retains significant virulence. Thus when this vaccine was administered to gray foxes it killed them. The infection was also transmitted from vaccinated to unvaccinated contacts. Subsequent analysis suggested that a single passage through foxes resulted in a measurable increase in viral virulence. Similar cases of distemper have been reported in young kinkajous (Potos flavus) and red pandas (Ailurus fulgens). The lethal effects of MLV CDV vaccine in black-footed ferrets are discussed below. It is assumed that the primary reservoirs of CDV are unvaccinated domestic dogs. However, other species such as raccoons may also be reservoir hosts. Distemper-infected ferrets (Mustela putorius faro) develop severe lymphopenia and secondary diarrhea, cutaneous lesions, and neurologic signs. Ferrets die within two weeks as a result of sepsis and multiorgan failure, and the disease is nearly 100% fatal. The only vaccine currently licensed in the United States for use in ferrets is a live canarypox vectored recombinant. It is given to ferrets over eight weeks of age, boosted three and six weeks later, and then revaccinated annually. There are also several inactivated vaccines that may also be given after 12 weeks and boosted annually. As with all other species, the decision to vaccinate should be subjected to a careful risk assessment. This may also influence any decision as to when to revaccinate. It has been suggested that ferrets are more likely to develop adverse events following distemper vaccination and that veterinarians should obtain signed consent forms before vaccinating ferrets. Some recommend pretreating ferrets with diphenhydramine, an antihistamine, before vaccinating them. Do not forget that ferrets must also be vaccinated against rabies. In addition to residual virulence, there have been several reports of injection site-associated sarcomas occurring in ferrets. These have been associated with the use of rabies and distemper vaccines. Canine, feline, and mink parvoviruses are closely related. Canids, felids, mustelids, procyonids, and viverrids are susceptible to at least one of these. Thus canids and mustelids such as otters should get canine parvovirus vaccines; exotic felids, raccoons, and mink should get feline panleukopenia vaccine. Only inactivated vaccines should be used in these species. Vaccines should be administered according to the manufacturer’s recommendations with annual revaccination. Some species such as lions may be less responsive to these vaccines than others such as tigers. Red wolves (Canis rufus) have positive antibody titers after three years, but otherwise the duration of immunity is unknown. Pigs of all species should also receive porcine parvovirus vaccination. Canine adenoviruses 1 and 2 can cause disease in foxes, wolves, coyotes, wild dogs, mustelids, binturongs (Arctictis binturong), and bears (Fig. 10.5). Cross-protection occurs between the two viral species so a single vaccine protects against both. Although a killed vaccine is not commercially available, this should be considered to be a core vaccine for captive canids. Risk of vaccine-induced disease exists because an MLV- CA2 vaccine has induced hepatitis in a maned wolf (Chrysocion brachyurus). In general, the vaccination protocol should be the same as used in domestic dogs. A core vaccine in exotic felids, the killed calicivirus vaccine may be administered in combination with feline rhinotracheitis vaccine. This is not a highly immunogenic vaccine and antibody responses are unpredictable. Annual revaccination is recommended. This is a core vaccine in exotic felids. Combined vaccines with feline panleukopenia are available. Timing of vaccination should be the same as recommended in domestic cats. Nondomestic equids are susceptible to the viral encephalitides. They should therefore receive bivalent (EEE-WEE) or trivalent (EEE-WEE-VEE) vaccines, perhaps in combination with tetanus toxoid. They should be primed with two doses three to four weeks apart with annual revaccination. It would be prudent to vaccinate tapirs in the same manner. Equine herpesviruses 1 and 4 can cause abortion in exotic equids. They should therefore receive a killed vaccine. They should be vaccinated at four months and at four-month intervals up to one year. Pregnant mares should be vaccinated during pregnancy (Chapter 15). Primates are susceptible to many of the infectious diseases that affect humans. It is usual to vaccinate them, especially the Pongidae, with children’s vaccines: mumps, measles and rubella, as well as diphtheria, pertussis, and tetanus (DPT). The great apes are also susceptible to poliomyelitis and they should therefore receive polio vaccine. The oral vaccine is easier to administer than the injectable one, but the modified live oral vaccine has the potential to cause disease. The oral vaccine may be administered on a sugar cube at six months, and then the animal should be isolated from unvaccinated primates for one month after vaccination. Should human polio vaccination be discontinued it would be no longer necessary to vaccinate captive primates. All mammals are susceptible to rabies. Therefore rabies vaccination should be considered essential in canids and felids and recommended for use in other mammals such as elephants where the potential for infection is high. Unfortunately, none of the currently available rabies vaccines are licensed for use in exotic captive mammals. The sole exception is for ferrets where killed vaccines are available for use in animals over 12 weeks of age. Ferrets must be vaccinated against rabies in an approved manner as prescribed in the compendium for rabies control. Most avian vaccines are licensed for use in commercial species such as poultry, mallards, and turkeys, but can probably be used safely in exotic species. Some vaccines designed for use in nonavian species are also routinely used in an “extra-label” manner to prevent disease. Nevertheless, infectious diseases remain a constant threat to pet birds. Although these threats stem mainly from viral infections, clostridial and mycoplasmal infections are examples of bacterial diseases that are better prevented or avoided than treated. Avian polyoma viruses (APV) cause acute mortality in fledgling budgerigars, nestling macaws, and finches. Adjuvanted and nonadjuvanted vaccines are available and used to vaccinate birds before shipment for commercial sales. Seroconversion does not differ significantly between the two vaccines. Pacheco disease, caused by Psittacid herpesvirus 1 (PDV), is an acute fulminating hepatitis resulting in up to 100% mortality in new world parrots. Survivors may eventually develop cloacal papillomas or hepatomas. Several oil-adjuvanted, inactivated vaccines have been developed against this disease. However, none appear to be commercially available at present. The oil emulsion adjuvanted vaccines may cause injection site reactions including swelling, muscle necrosis, or granuloma formation. Cockatoos appear to be especially sensitive to these types of reactions. Since its introduction to North America in 1999, West Nile Virus (WNV) has spread across both American continents causing neurological disease in humans, horses, and many species of birds. WNV is maintained in the wild in a transmission cycle between birds and mosquitoes. Corvids are highly susceptible to WNV infection. Other susceptible North American birds include some endangered or threatened species. As in humans, juvenile and aged birds may be more susceptible to disease. Although a clear threat, no avian-specific WNV vaccine is available. Therefore valuable susceptible species, especially captive cranes, raptors, penguins, flamingos, and corvids may be vaccinated using equine vaccines. The formalin inactivated, adjuvanted whole virus vaccine, West Nile Innovator, has been used extensively in birds, especially in emergency situations where it is considered essential to protect large valuable populations. For example, this vaccine has been tested in Sandhill cranes (Antigone canadensis). Other species that have received this vaccine include penguins, flamingos, and prairie chickens. All were vaccinated intramuscularly at least twice and no adverse effects were reported. WNV vaccination has also been undertaken in California condors (Gymnogyps californianus), both in captivity and in the wild. Influenza vaccines have been used in species other than poultry. For example, birds have been vaccinated against avian influenza virus using an inactivated H5N9 vaccine. Significant species variation in response was noted. Vaccination may provide protection from highly pathogenic avian influenza outbreaks in zoos and should be regarded as an important adjunct procedure in addition to increased biosecurity and monitoring. Newcastle disease virus (NDV) vaccines are used in commercial ostrich flocks. Ostriches respond to vaccination with LaSota strain NDV vaccines. NDV causes neurologic disease and diarrhea in pigeons. As a result, racing pigeons are commonly vaccinated using the LaSota strain of NDV. Adult birds are given the chicken vaccine by eye drop seven weeks before breeding. Annual revaccination is recommended. Vaccination may be mandatory for racing pigeons in many countries. A single vaccination gave protection lasting one year. Paratyphoid caused by Salmonella typhimurium var. Copenhagen, is a problem in many pigeon lofts. A killed adjuvanted vaccine (KM-1) is given subcutaneously to pigeons over five weeks of age and boosted three to four weeks later. It contains a mixture of pigeon isolates. Annual revaccination is also recommended. Pigeons also suffer from pigeon pox and circovirus infections and some pigeon breeders may elect to use extra-label poultry vaccines in their birds despite the lack of evidence of efficacy. Avipoxvirus infections occur in many domestic, pet, and wild bird species. These viruses are spread either by mosquito bites or via aerosol. Many different vaccines are available to control fowlpox infections in poultry. A chicken fowlpox vaccine has been reported to protect zebra finches. A live pigeon pox vaccine has been tested in falcons. There is a commercially available live attenuated canarypox vaccine (Poximune C, Ceva Biomune) available for use in canaries. It is administered through the wing web and an obvious reaction occurs at the site 7 to 10 days later. Birds should be revaccinated at 6 to 12 month intervals. Birds should also be revaccinated four weeks before laying or the beginning of the mosquito season. Mink are intensively farmed for their fur. As a result of high stocking density, infectious diseases are a constant threat. It is important to remember that the pelt is the most valuable product from these animals. Injection site lesions thus present a special problem. Vaccine site infections with Arcanobacterium phocae are also an emerging issue. This bacterium causes a severe necropurulent dermatitis at the injection site in the hind leg and is believed to be the cause of a skin disease, fur animal epidemic necrotic pyoderma, in mink, foxes, and raccoons. The use of cheap, low-quality food has resulted in serious food poisoning episodes, especially botulism from rotting meat among mink. Cl. botulinum type C grows and produces its toxin when contaminated meat is stored at temperatures over 15°C and anaerobic growth can occur. When this meat is consumed, mink die within 24 to 72 hours with paralysis and dyspnea. Losses may reach 100%. Cl. botulinum type C toxoid is available for use in mink. It may be given to kits as early as six to seven weeks of age. Protection develops in three weeks. Annual revaccination is encouraged. Mink are highly susceptible to canine distemper. Attenuated live CDV vaccines produce prolonged dependable immunity. Inactivated vaccines have given erratic results in mink. Historically, such vaccines were made by formalizing infected mink tissues. On occasion however, the formaldehyde failed to inactivate contaminating Aleutian disease parvovirus. As a result, outbreaks of Aleutian disease caused serious losses. Almost all young mink in North America receive a single dose of distemper vaccine during the summer after they reach 10 weeks of age and maternal antibodies have waned. Revaccination may not be necessary because of herd immunity and the fact that mink are generally pelted around three years of age. Mink distemper vaccine is commonly given as a 3- or 4-way vaccine with pseudomonas, enteritis, and botulism. Mink virus enteritis is caused by a parvovirus that is closely related to the feline and canine parvoviruses. In kits, mortality may reach 75%. Only inactivated vaccines are available commercially. Kits may be vaccinated at 10 to 13 weeks of age. Breeding mink should be revaccinated annually. Parvovirus vaccines are commonly combined with vaccines against botulism, distemper, and Pseudomonas. Pseudomonas aeruginosa causes hemorrhagic pneumonia in mink. It is associated with the stress of the warm days in the fall. The mink show lethargy and anorexia progressing to respiratory disease and death. Successful vaccination requires immunization with all the pathogenic serotypes. Pseudomonas bacterins should contain serotypes 5, 6, 7, and 9. Like the other vaccines, it should be administered after maternal antibodies have waned. Adult mink should be revaccinated annually. A killed bacterin against Pasteurella multocida for the prevention of rabbit “snuffles” is available in North America. Rabbit hemorrhagic disease is a highly contagious disease of European rabbits caused by small, single-stranded RNA caliciviruses. There are two such viruses: classical rabbit hemorrhagic disease virus-1 (RHDV-1) and a variant virus, (RHDV-2 or RHDVb). RHDVs cause a disease characterized by convulsions, paralysis, and respiratory signs, including depression and inappetence. Morbidity and mortality may reach up to 90% within 36 hours. In captivity, transmission is by the oral-fecal route. In the wild it is likely spread by mosquitos and fleas. In countries where RHD is endemic, the disease is controlled by good biosecurity and variant-specific vaccination. If the virus type is unknown then vaccination should be directed against both variants because cross-protection between RHDV-1 and -2 vaccines is variable and unpredictable. Both monovalent and bivalent inactivated adjuvanted vaccines against RHDV are available. Most are directed against RHDV2 but a bivalent product is preferable. The first injection is given subcutaneously between four weeks and two months depending upon the product. It is usual to vaccinate only breeding stock and they should be revaccinated at six months. Immunity develops in 7 to 10 days and persists for over a year. They do not protect rabbits against myxomatosis This disease is caused by the myxoma virus (MYXV), a member of the Poxviridae family. Its natural hosts are found in South America and California. Myxomatosis is characterized by the development of large skin lesions accompanied by immunosuppression or respiratory disease. Mortality varies from 20% to 100% in European rabbits. Two types of modified live vaccine have been developed. One has been prepared from the Shope fibroma virus (SFV), an avirulent Leporipoxvirus. The others are prepared from attenuated strains of MYXV. Both may be administered subcutaneously or intradermally. The SFV vaccines are somewhat less immunogenic and are no longer used in the meat rabbit industry. The live attenuated MYXV vaccines are more immunogenic and protection lasts for four to six months. They should be followed by annual revaccination. However, these vaccines are immunosuppressive. A recombinant live MYXV vectored vaccine expressing the rabbit hemorrhagic disease virus capsid protein and thus protecting against both of these important diseases is available in Europe. Many infections in humans and their animals come from wildlife reservoirs. These may include major public health zoonoses such as rabies and sylvatic plague, or threats to livestock such as brucellosis, anthrax, pseudorabies, classical swine fever, and tuberculosis. In many cases lethal control procedures may neither be feasible nor acceptable. An alternative control strategy is oral vaccination. This has been highly successful for rabies and encouraging results have been observed for sylvatic plague. For oral vaccination to work three factors must come together: an effective oral vaccine, a suitable way of delivering it, and a species-specific bait. Wild caught carnivores have a high risk of transmitting rabies and should not be kept as pets. Indeed, this is illegal in many areas. Do not assume that a baby animal is not infected. Foxes, raccoons, and skunks may acquire infection at an early age and may incubate the disease for more than a year. In the United States, wild mammals account for over 90% of human rabies exposures. If vaccination of pet wildlife is necessary then only killed vaccines should be used. More importantly, wild animals must be vaccinated if rabies is to be controlled. This requires the oral administration of vaccines. It needs an economical and effective vaccine, a vaccine that is environmentally stable, and a vaccine that works extremely well by the oral route. Several different vaccines have been used in oral rabies vaccination programs. Most have used a live, attenuated rabies virus. More than 13 million doses of the attenuated rabies strain, ERA-BHK21 were distributed across Eastern Ontario to control the disease. In Europe, more than 650 million doses were distributed between 1978 and 2014 using attenuated SAD (Street-Alabama-Dufferin) Bern, its derivative strain SAD B19 or SAG2 (SAD Avirulent Gif). More recently, wildlife vaccinators have switched to recombinant vaccines using either vaccinia or adenovirus vectors. For example, the gene for the rabies envelope glycoprotein, (G-protein), from the avirulent ERA strain has been inserted into a vaccinia vector (RABORAL V-RG, Boehringer Ingelheim). When this is ingested, the resulting infection induces neutralizing antibodies to the G-protein and the development of immunity within 10 to 14 days. This vaccine is distributed in a small plastic sachet and either surrounded by solid fishmeal polymer (FP bait), or coated with wax and fishmeal crumbs (CS bait) (Fig. 20.1). It may also contain tetracycline as a biomarker because this will stain the recipient’s teeth. RABORAL V-RG is licensed for use in the United States in coyotes, raccoons, and gray foxes.
Vaccination of exotic and wild species
Mammals
Erysipelas
Leptospirosis
Clostridial diseases
Bovine herpesvirus 1
Parainfluenza 3
Canine distemper
Parvoviruses
Canine adenovirus
Feline calicivirus
Feline herpesvirus
Equine encephalitides
Equine herpesvirus
Human vaccines
Rabies
Birds
Avian polyoma virus
Herpesviruses
West nile virus (WNV)
Avian influenza
Newcastle disease
Other pigeon vaccines
Poxviruses
Commercial exotic vaccines
Mink vaccines
Botulism
Canine distemper
Mink virus enteritis
Hemorrhagic pneumonia
Rabbit vaccines
Rabbit pasteurellosis
Rabbit hemorrhagic disease
Myxomatosis
Wildlife vaccines
Rabies
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