Vaccinating and healing sick and injured animals

Diseases and injuries are another source of misery for nonhuman animals living in the wild. But, fortunately, this is one of the fields in which we currently know of significant ways to help them. Diseases in nature explains this in some detail. Many environmentalists hold the opinion that wild animals should not be helped because it is not “natural” or because we shouldn’t be concerned about individual animals. But once we see the arguments why speciesism should be rejected and if we oppose discrimination against animals, we recognize that there are no valid reasons to not try to help any animals when we can.


Animals suffering from diseases and injuries

Fortunately, there are experiences that show that it is often perfectly feasible to intervene in nature to provide animals with health aid. What’s more, some of us may be in situations in which we are able to provide first aid or general assistance to animals who are injured or sick.

Gorilla Doctors

Treatment of lungworm infection of bighorn sheep


Vaccinating animals in the wild

Apart from assistance to animals who are already sick or injured, an important way we can help animals in the wild to be free from diseases is through vaccination. There are many examples of vaccinations of animals living in the wild on a large scale. Perhaps the most important case among these is that of vaccination against rabies, which has been carried out in several different countries on a large scale. Vaccinations against many other diseases that wild animals suffer from have also been developed.


Oral rabies vaccination

One paradigmatic example of wild animal immunization is the vaccination of animals against rabies1 that successfully eradicated the disease in most of Europe by 2010 and in large areas of North America. This was done in order to prevent the disease from spreading and being passed on to animals living with humans, such as dogs, or to humans themselves. The vaccination was administered through the aerial dispersal of baits containing rabies vaccine that were then eaten by the animals.2

In the US, attempts to eliminate the disease started in the 70s3 and it was achieved in Parramore Island, Virginia,4 Williamsport, Pennsylvania5 and Cape May, New Jersey.6 Other efforts have been made in other parts of North America, such as Canada,7 though it is the USA which currently leads the way in oral vaccination programs. One such program was the prevention of the spread of rabies in the free-ranging raccoons of Massachusetts by orally vaccinating 63% of the population, which was sufficient for a successful eradication of the disease in the area.8 Another example is the oral rabies vaccination program for coyotes in Texas which led to a significant reduction of rabies cases as well as stopping its growth in the affected area.9 A coordinated effort between the USA, Mexico and Canada has been proposed in order to eradicate rabies in North American wild carnivores.10

Similar programs have been implemented all over the world, including dog vaccination in Africa11 and Asia.12 The data from these programs provide evidence of efficacy and specifics of implementation that will make it easier to vaccinate more animals in the future.

Rabies is an appalling disease for those animals affected by it. Even though in the above cases animals are not vaccinated to protect them from harm but rather to protect humans or domesticated animals, preventing them from contracting the disease can obviously benefit them immensely.


Ebola and great apes

The strain of Ebola in Zaire has killed approximately one third of the world’s gorilla population and around the same proportion of chimpanzees.13 It seems that vaccination would be an obvious solution to fight this disease. In fact, this is precisely what has been suggested by organizations such as Vaccinape, which proposes vaccination to save the lives of African great apes. The vaccination procedure consists of either vaccines in bait, as used for rabies vaccines, or hypodermic darts.

There is more interest in treating great apes because their species is generally highly valued, and also because of recent threats to human health that have spread through contact with or consumption of infected apes. Other animals may not receive the same attention, but other animals could be treated similarly.


Hepatitis B and gibbons

There are other serious diseases, more often associated with human beings, which also cause a great deal of suffering and death for wild animal populations. Hepatitis B and tetanus are common diseases among gibbons, along with measles and rabies. In order to reduce the risk of transmission, both from humans to gibbons and vice versa, the Wild Animal Rescue Foundation of Thailand recommends the vaccination of gibbons and human workers for all these diseases.14


Swine fever and wild boars

In 2013, The European Commission backed a proposal for the vaccination of wild boars in order to improve the health of domestic pigs. The breakout of swine fever in 1997 resulted in the deaths of over 10 million pigs. An orally administered vaccine will give preventive immunity to wild boars and it can also be used for emergency inoculations of domesticated pigs.15


Vaccination to control animal diseases in the UK

The United Kingdom is probably the place where the immunization of animals against disease is most normalized. Vaccination is widely implemented to protect animals from diseases such as Avian Influenza or Newcastle Disease in birds. Despite its name, Newcastle Disease has long been proliferating outside Newcastle. For example, recently in China, 1,989 peacocks were vaccinated in Yunnan Wild Animal Park against avian influenza virus and Newcastle disease.16

In the UK there is a Vaccine and Antigen Bank where the government keeps supplies to be used in potential outbreaks, or to be deployed for conservation such as for penguins and parrots. The UK also contributes to the EU Vaccine Bank for Classical Swine Fever as well as to the high priority Foot and Mouth antigens bank, where antigens and vaccines are kept ready to be used when needed.17



Wild animals used in human hunting sometimes become infected with serious diseases for which vaccination has been employed. Anthrax, for example, an acute and lethal disease, usually infects herbivorous mammals as well as the carnivores that prey upon them. Given the high risk of the disease spreading to humans, particularly due to the consumption of the flesh of hunted animals, immunization trials have already been carried out. A pilot vaccination program was developed for vaccination against anthrax of animals typically hunted in so-called African “game parks.” Guinea pigs were orally and subcutaneously vaccinated, and they developed successful levels of resistance to the infection.18


Black death, prairie dogs, and ferrets

The devastating effects of “Black Death” pandemics on human populations are familiar to almost everybody. Not so familiar are the mortality rates of wild rodents who still succumb to the disease today. Recently, in South Dakota, the plague decimated a population of prairie dogs and has consequently affected their natural predators, black-footed ferrets. Since black-footed ferrets are among the most endangered mammals in North America, efforts have been made to vaccinate them. However, the capture and injection of ferrets with the vaccine has proven less effective than a mass immunization of prairie dogs. Prairie dogs have shown a survival rate of more than 95 per cent of those infected after they are vaccinated.19 Even though the aim of the vaccination is the protection of ferrets, prairie dogs are also benefiting from it. At least, that is, until they are preyed upon by healthy ferrets.


Brucellosis and buffalos

Buffalo populations at Yellowstone National Park are highly vulnerable to Brucellosis disease. In order to reduce the risk of transmission from buffalos to domesticated animals used for food, the Interagency Buffalo Management Plan includes a vaccination program for resident or migrating buffalos within the area.20 Helping buffalos for their own sake, irrespective of the danger they might pose to the health of animals used for food or the economy, could also be considered.


Tuberculosis and wild boars

Tuberculosis is still an active disease acting on both human and nonhuman individuals. In 2011, an oral vaccine was delivered in bait to free-living wild boars under natural conditions of transmission.21


Reducing the spread of disease by vector insects

In other cases, it is not possible to stop the spread of a disease by vaccinating animals, and other measures are needed to stop it. This is the case, for instance, with diseases that are transmitted by animals such as ticks or insects.

One way to prevent the spread of such a disease would be to kill the insects carrying it, but this would obviously be harmful to them. There are other ways of reducing the populations of vector insects which do not involve killing animals and which are actually more successful. This can be done by sterilizing them or by a treatment that causes more males to be born than females. Some people may think this is immoral, but this can hardly be so when the alternative is the agony and death many animals would otherwise face because of the disease, in addition to the death of a huge number of the insects themselves due to their population dynamics.

One technique used for this purpose, inherited sterility, consists of spreading individuals from a certain species whose progeny will be sterile into a target area.22 The males are treated in a way which causes them to have fewer offspring, most of whom will be sterile. This also causes more males than females to be born.23

The sterilization of insects has already been carried out on a global scale. It was initially developed in the 1940s24 and has been evolving since then.

Examples of successful uses of this technique are the following:

  • Tsetse flies can transmit human sleeping sickness and elephantiasis. They also transmit animal trypanosomiasis. In Tanzania in the 1940s this disease was eradicated by sterilizing Tsetse flies. During the following decades, it was also used in countries such as Burkina Faso, Nigeria and Uganda. Mosquito Culex quinquefasciatus (earlier known as Culex fatigans) is the vector of lymphatic filariasis, a painful and disfiguring disease which infects humans in India, Myanmar and Florida.
  • Another mosquito species, Aedes aegypti transmits dengue, as well as yellow fever, chikungunya fever and other diseases. Sterilization was used in the 1970s in Kenya to eliminate this disease.
  • Culex pipiens is the vector of several diseases including meningitis, Japanese encephalitis and West Nile virus. Sterilization was used for this in France in the 1970s.
  • Another species of mosquito, the Anopheles albimanus, transmits malaria. Sterilization was done in El Salvador in the 1970s.

Of course, this may have some consequences for the natural processes that occur in these areas. Nevertheless, it is widely assumed that it is worth carrying out these measures, because it will save the lives of a great number of human beings. As it is human lives which are at stake, this measure is generally accepted as fully justified. Because of the speciesist bias that exists, measures such as vaccination and the sterilization of vector insects is considered fully acceptable when it benefits humans but not when it only aids nonhuman animals.25 However, because speciesism is morally unjustified, we have to reject this way of thinking.

Further readings

Anderson, N. & Smith, I. (2019) “Assessing the immunogenicity of an inactivated monovalent vaccine in the endangered African wild dog (Lycaon pictus)”, Vaccine: X, 1 [accessed on 4 June 2019].

Arnold, M. E.; Paton, D. J.; Ryan, E.; Cox, S. J. & Wilesmith, J. W. (2007) “Modelling studies to estimate the prevalence of foot-and-mouth disease carriers after reactive vaccination”, Proceedings of the Royal Society B: Biological Sciences, 275.

Bovenkerk, B.; Stafleu, F.; Tramper, R.; Vorstenbosch, J. & Brom, F. W. A. (2003) “To act or not to act? Sheltering animals from the wild: A pluralistic account of a conflict between animal and environmental ethics”, Ethics, Place and Environment, 6, pp. 13-26.

Chambers, M. A.; Rogers, F.; Delahay, R. J.; Lesellier, S.; Ashford, R.; Dalley, D.; Gowtage, S.; Davé, D.; Palmer, S.; Brewer, J.; Crawshaw, T.; Clifton-Hadley, R.; Carter, S.; Cheeseman, C.; Hanks, C.; Murray, A.; Palphramand, K.; Pietravalle, S.; Smith, G. C.; Tomlinson, A.; Walker, N. J.; Wilson, G. J.; Corner, L. A. L.; Rushton, S. P.; Shirley, M. D. F.; Gettinby, G.; McDonald R. A. & Hewinson, R. G. (2010) “Bacillus Calmette-Guérin vaccination reduces the severity and progression of tuberculosis in badgers”, Proceedings of the Royal Society B: Biological Sciences, 278 [accessed on 15 May 2019].

Delahay, R. J.; Smith, G. C. & Hutchings, M. R. (2009) Management of disease in wild mammals, Dordrecht: Springer.

Galizi, R.; Doyle, L. A.; Menichelli, M.; Bernardini, F.; Deredec, A.; Burt, A.; Stoddard, B. L.; Winbichler, N. & Crisanti, A. (2014) “A synthetic sex ratio distortion system for the control of the human malaria mosquito”, Nature Communications, 5, 3977 [accessed on 23 June 2014].

González-Barrio, D. & Ruiz-Fons, F. (2019) “Coxiella burnetii in wild mammals: A systematic review”, Transboundary and Emerging Diseases, 66, pp. 662-671.

Harris, R. N. (1989) “Nonlethal injury to organisms as a mechanism of population regulation”, The American Naturalist, 134, pp. 835-847.

Holmes, J. C. (1995) “Population regulation: a dynamic complex of interactions”, Wildlife Research, 22, pp. 11-19.

Laughlin, R. C.; Madera, R.; Peres, Y.; Berquist, B. R.; Wang, L.; Buist, S.; Burakova, Y.; Palle, S.; Chung, C. J.; Rasmussen, M. V.; Martel, E.; Brake, D. A.; Neilan, J. G.; Lawhon, S. D.; Adams, L. G.; Shi, J. & Marcel, S. (2019) “Plant‐made E2 glycoprotein single‐dose vaccine protects pigs against classical swine fever”, Plant Biotechnology Journal, 17, pp. 410-420 [accessed on 28 May 2019].

Nermeen, G. S.; Darwish, D. M.; Abousenna, M. S.; Galal, M.; Ahmed, A. R.; Attya, M.; Saad, M. A. & Abdelhakim, M. (2019) “Efficacy of a commercial local trivalent Foot and Mouth Disease (FMD) vaccine against recently isolated O-EA3”, International Journal of Veterinary Science, 8, pp. 35-38 [accessed on 1 May 2019].

Newton, I. (1998) Population limitations in birds, San Diego: Academic Press.

Ng, Y.-K. (1995) “Towards welfare biology: Evolutionary economics of animal consciousness and suffering”, Biology and Philosophy, 10, pp. 255-285.

Nussbaum, M. C. (2006) Frontiers of justice: Disability, nationality, species membership, Cambridge: Harvard University Press.

Robinson, S. J.; Barbieri, M. M.; Murphy, S.; Baker, J. D.; Harting, A. L.; Craft, M. E. & Littnan, C. L. (2018) “Model recommendations meet management reality: Implementation and evaluation of a network-informed vaccination effort for endangered Hawaiian monk seals”, Proceedings of the Royal Society B: Biological Sciences, 285 [accessed on 3 June 2019].

Saggese, K.; Korner-Nievergelt, F.; Slagsvold, T. & Amrhein, V. (2011) “Wild bird feeding delays start of dawn singing in the great tit”, Animal Behaviour, 81, pp. 361-365.

Schliekelman, P.; Ellner, S. & Gould, F. J. (2005) “Pest control by genetic manipulation of sex ratio”, Journal of Economical Entomology, 98, pp. 18-34.

Tomasik, B. (2015) “The importance of wild animal suffering”, Relations: Beyond Anthropocentrism, 3, pp. 133-152 [accessed on 3 January 2016].

Tompkins, D. M.; Ramsey, D. S. L.; Cross, M. L.; Aldwell, F. L.; de Lisle, G. W. & Buddle, B. M. (2009) “Oral vaccination reduces the incidence of tuberculosis in free-living brushtail possums”, Proceedings of the Royal Society B: Biological Sciences, 276 [accessed on 3 May 2019].

Tsiodras, S.; Korou, L.-M.; Tzani, M.; Tasioudi, K. E.; Kalachanis, K.; Mangana-Vougiouka, O.; Rigakos, G.; Dougas, G.; Seimenis, A. M. & Kontos, V. (2016) “Rabies in Greece; historical perspectives in view of the current re-emergence in wild and domestic animals”, Travel Medicine and Infectious Disease, 12, pp. 628-635.

Turner, J. W., Jr.; Liu, I. K. M.; Flanagan, D. R.; Rutberg, A. T. & Kirkpatrick, J. F. (2001) “Immunocontraception in feral horses: One inoculation provides one year of infertility”, Journal of Wildlife Management, 65, pp. 235-241.

Wobeser, G. A. (2005) Essentials of disease in wild animals, New York: John Wiley and Sons.


1 Steck, F.; Wandeler, A.; Bichsel, P.; Capt, S.; Hafliger, U. & Schneider, L.G. (1982) “Oral immunization of foxes against rabies. Laboratory and field studies”, Comparative Immunology, Microbiology and Infectious Diseases, 5, pp. 165-171.

2 The procedure of oral vaccination of foxes is described here: Department for Environment, Food and Rural Affairs (2010) Vaccination as a control tool for exotic animal disease: Key considerations, London: Department for Environment, Food and Rural Affairs [accessed on 10 August 2013].

3 Baer, G. M.; Abelseth, M. K. & Debbie, J. G. (1971) “Oral vaccination of foxes against rabies”, American Journal of Epidemiology, 93, pp. 487-490.

4 Hanlon, C. A.; Niezgoda, M.; Hamir, A. N.; Schumacher, C.; Koprowski, H. & Rupprecht, C. E. (1998) “First North American field release of a vaccinia-rabies glycoprotein recombinant virus”, Journal of Wildlife Diseases, 34, pp. 228-239.

5 Hanlon, C. A. & Rupprecht, C. E. (1998) “The reemergence of rabies, in Scheld, D.; Armstrong, J. M.; Hughes, J. B. (eds.) Emerging infections I, Washington, D. C.: ASM Press, pp. 59-80.

6 Rosatte, R.; Donovan, D.; Allan, M.; Howes, L. A.; Silver, A.; Bennett, K.; MacInnes, C.; Davies, C.; Wandeler, A. & Radford, B. (2001) “Emergency response to raccoon rabies introduction into Ontario”, Journal of Wildlife Diseases, 37, pp. 265-279.

7 MacInnes, C. D. & LeBer, C. A. (2000) “Wildlife management agencies should participate in rabies control”, Wildlife Society Bulletin, 28, pp. 1156-1167. MacInnes, C. D.; Smith, S. M.; Tinline, R. R.; Ayers, N. R.; Bachmann, P.; Ball, D. G. A.; Calder, L. A.; Crosgrey, S. J.; Fielding, C.; Hauschildt, P.; Honig, J. M.; Johnston, D. H.; Lawson, K. F.; Nunan, C. P.; Pedde, M. A.; Pond, B.; Stewart, R. B. & Voigt, D.R. (2001) “Elimination of rabies from red foxes in eastern Ontario”,Journal of Wildlife Diseases, 37, pp. 119-132.

8 Robbins, A. H.; Borden, M. D.; Windmiller, B.S.; Niezgoda, M.; Marcus, L. C.; O’Brien, S. M.; Kreindel, S. M.; McGuill, M. W.; DeMaria, A., Jr.; Rupprecht, C. E. & Rowell, S. (1998) “Prevention of the spread of rabies to wildlife by oral vaccination of raccoons in Massachusetts”, Journal of the American Veterinary Medical Association, 213, pp. 1407-1412.

9 Fearneyhough, M. G.; Wilson, P. J.; Clark, K. A.; Smith, D. R.; Johnston, D. H.; Hicks, B. N. & Moore, G. M. (1998), “Results of an oral rabies vaccination program for coyotes”, Journal of the American Veterinary Medical Association, 212, pp. 498-502.

10 Slate, D.; Rupprecht, C. E.; Rooney, J. A.; Donovan, D.; Lein, D. H.; Chipman, R.B. (2005) “Status of oral rabies vaccination in wild carnivores in the United States”, Virus Research, 111, pp. 68-76.

11 Cleaveland, S.; Kaare, M.; Tiringa, P.; Mlengeya, T. & Barrat, J. (2003) “A dog rabies vaccination campaign in rural Africa: impact on the incidence of dog rabies and human dog-bite injuries”, 21, pp. 1965-1973. Kitala, P. M.; McDermott, J. J.; Coleman, P. G. & Dye, C. (2002) “Comparison of vaccination strategies for the control of dog rabies in Machakos District, Kenya”, Epidemiology and Infection, 2002, 129, pp. 215-222.

12 Childs, J. E.; Robinson, L. E.; Sadek, R.; Madden, A.; Miranda, M. E. & Miranda, N. L. (1998) “Density estimates of rural dog populations and an assessment of marking methods during a rabies vaccination campaign in the Philippines”, Preventive Veterinary Medicine, 33, pp. 207-218. Pal, S. K. (2001) “Population ecology of free-ranging urban dogs in West Bengal, India”, Acta Theriologica, 46, pp. 69-78.

13 Torres, E. (2012) “Should we vaccinate wild apes?”, February 16 [accessed on 2 July 2013].

14 Wild Animal Rescue Foundation of Thailand (2007) “Information”, [accessed on 15 July 2013].

15 García-Belmonte, R.; Pérez-Núñez, D.; Pittau, M.; Richt, J. A. & Revilla, Y. (2019) “African swine fever virus Armenia/07 virulent strain controls interferon beta production through the cGAS-STING pathway”, Journal of Virology, 93, pp. 13-26 [accessed on 3 June 2019].

16 He, T. (2010) “1,989 peacocks vaccinated in Yunnan Wild Animal Park”, Kunming [accessed on 3 August 2013].

17 Department for Environment, Food and Rural Affairs (2010) Vaccination as a control tool for exotic animal disease: Key considerations, op. cit.

18 Rengel, J. & Böhnel, H. (1994) “Vorversuche zur oralen Immunisierung von Wildtieren gegen Milzbrand”, Berliner und Münchener tierärztliche Wochenschrift, 107, pp. 145-149.

19 Leggett, H. (2009) “Plague vaccine for prairie dogs could save endangered ferret”, Wired, 08.04.09 [accessed on 25 July 2013].

20 Buffalo Field Campaign (2008) “Vaccination of wild buffalo fact sheet”, [accessed on 4 June 2019].

21 Garrido, J. M.; Sevilla; I. A.; Beltrán-Beck, B.; Minguijón, E.; Ballesteros, C.; Galindo, R. C.; Boadella, M.; Lyashchenko, K. P.; Romero, B.; Geijo, M. V.; Ruiz-Fons, F.; Aranaz, A.; Juste, R. A.; Vicente, J.; de la Fuente, J. & Gortázar, C. (2011) “Protection against tuberculosis in Eurasian wild boar vaccinated with heat-inactivated Mycobacterium bovis”, PLOS One, 6 (9) [accessed on 19 July 2013].

22 Dyckn, V. A.; Hendrichs, J. & Robinson, A. S. (eds.) (2005) Sterile insect technique, Dordrecht: Springer. Parker, A. & Mehta, K. (2007) “Sterile insect technique: a model for dose optimization for improved sterile insect quality”, Florida Entomologist, 90, pp. 88-95. Alphey, L.; Benedict, M.; Bellini, R.; Clark, G. G.; Dame, D. A.; Service, M. W. & Dobson, S. L. (2010) “Sterile-insect methods for control of mosquito-borne diseases: An analysis”, Vector-borne and zoonotic diseases, 10, pp. 295-311.

23 Gemmell, N. J.; Jalilzadeh, A.; Didham, R. K.; Soboleva, T. & Tompkins, D. M. (2013) “The Trojan female technique: A novel, effective and humane approach for pest population control”, Proceedings of the Royal Society B: Biological Sciences, 280 [accessed on 31 August 2018].

24 This method was initially implemented to fight parasitism, and has been used for this purpose also since then. It has been applied in the case of New World screw-worm fly (Cochliomyia hominivorax) in places including the US (Florida and Texas), Central America, the Netherlands Antilles and Lybia.

25 See Loftin, R. W. (1985) “The medical treatment of wild animals”, Environmental Ethics, 7, pp. 231-239.

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