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The One Health Paradigm and Wild Animal Welfare Science

Published online by Cambridge University Press:  08 May 2026

Oscar Horta Open the ORCID record for Oscar Horta [Opens in a new window]  and
Iria Murado-Carballo Open the ORCID record for Iria Murado-Carballo [Opens in a new window]
Oscar Horta*
Affiliation:
Research Institute for the Humanities, University of Santiago de Compostela, Spain
Iria Murado-Carballo
Affiliation:
Research Institute for the Humanities, University of Santiago de Compostela, Spain
*
Corresponding author: Oscar Horta; Email: oscar.horta@usc.gal
Rights & Permissions [Opens in a new window]

Abstract

Initiatives protecting wild animal health, including vaccination campaigns, medical treatments, and parasite control programs, have been implemented for decades. Their goal has been to safeguard human well-being, as well as to further conservationist goals. This paper argues that the well-being of wild animals, considered as sentient individuals, should be another crucial reason to expand these measures. Rather than treating animal health in a purely instrumental manner, this perspective aligns more closely with the ethos of the One Health paradigm. The paper presents examples of existing programs that benefit wild animals and could be broadened based on this idea. Next, it explains the kind of cross-disciplinary research framework—integrating animal welfare science, ecology, and other disciplines—needed to successfully develop effective ways to help wild animals. It then argues that the reasons to protect wild animal health also apply in the case of other ways to help wild animals. This is relevant especially in light of the very large scale of wild animal suffering.

Keywords

One Healthwild animal welfarewild animal sufferingwild animal healthwild animal ethics

Information

Type
Research Article
Information
Cambridge Quarterly of Healthcare Ethics , First View , pp. 1 - 11
Creative Commons
Creative Common License - CCCreative Common License - BY
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.
Copyright
© The Author(s), 2026. Published by Cambridge University Press

Introduction

Measures aiming at safeguarding wild animals’ health, including vaccination, medical treatment programs, and parasite eradication campaigns, have been implemented for several decades already. This practice aligns with the One Health paradigm, defined by leading international health organizations, as “an integrated, unifying approach that aims to sustainably balance and optimize the health of people, animals and ecosystems”.Footnote 1 Footnote 2, Footnote 3, Footnote 4 However, while the One Health stresses interdependence between the health of humans and nonhuman animals, it is commonly appealed to in ways that regard the protection of animal health as useful or necessary only instrumentally. There are mainly two goals of why programs aiming at safeguarding the health of wild animals: to prevent zoonotic diseases that may be passed onto other animals that are used as resources (mostly those in farms) or to humans and to promote conservationist goals, such as preventing potential extinctions of species or populations. In some cases, there may be other reasons backing these measures, as it happens in the case of those aiming at protecting the health of bees for the sake of preventing negative impacts in agriculture due to pollination collapses.Footnote 5 But these have almost always been reasons focused on human interests. In contrast, the well-being of the animals affected by them has not been considered so far in these types of measures but marginally.

This neglect is problematic, as there are good reasons to conclude that the well-being of animals is important and should count in favor of initiatives to aid wild animals. This aligns better with the One Health paradigm and gives us reasons to expand present efforts to safeguard wild animal health beyond what a mere anthropocentric or conservationist approach would imply. To argue for this view, in Section “Initiatives protecting the health of wild animals,” we present some examples of measures currently implemented to protect wild animal health. Then, in Section “Animals’ well-being as a key consideration in protecting animal health,” we explain how they align with the way the One Health approach is often understood, according to which human health (and sometimes conservation) matters, but not the well-being of animals. This also occurs in the case of the EcoHealth and Planetary Health paradigms. We argue, against this, that that there are sound reasons to grant nonhuman animals robust moral consideration. Next, in Section “How giving animals moral consideration makes a difference,” we present examples of how taking the well-being of animals seriously can make a difference regarding the kind of initiatives protecting wild animal health that could be fostered. In Section “Wild animal welfare science,” we explain the kind of cross-disciplinary research needed to expand our capacity to do work of this kind, which involves learning more about how to help wild animals through work in animal welfare science, ecology, and other fields. Then, in Section “The importance of wild animals’ well-being (and ill-being),” we argue that considerations similar to those in favor of protecting the health of wild animals apply to other ways wild animals can be protected from other harms they suffer. We indicate some of the factors that are severely detrimental to animal well-being and explain why the scale of wild animal suffering is vast. Finally, in Section “Conclusion,” we draw together the key insights discussed throughout the article..

Initiatives protecting the health of wild animals

A very large number of animals around the world have been helped by initiatives protecting their health in ways that benefit humans. Some representative examples include the following.

Vaccination

Wild animal vaccination programs have targeted a range of diseases. Most wild animals have been vaccinated with oral vaccine baits, which have a smell and taste attractive to animals of the target species. Distribution can be conducted at the ground level, although at large scale it often involves dropping the dose baits from the air, using light aircrafts, helicopters, or drones. This makes it possible to cover extensive areas, including those that would otherwise be hard to reach. Air drops have been used, in particular, in wild animal vaccination programs against rabies, which have targeted diverse species typically affected by this disease, significantly reducing its impact in North AmericaFootnote 6 and across Western and Central Europe.Footnote 7 Oral vaccination programs have also been implemented for other diseases like classical swine fever in wild boars,Footnote 8 sylvatic plague in prairie dogs,Footnote 9 and Lyme disease in rodents.Footnote 10 Other methods, such as aerosolized vaccines for diseases like tuberculosis in possums,Footnote 11 can also be effective.

Medical interventions

In some cases, animals are not (or not just) vaccinated against certain diseases but actually treated when they are affected by them. There are many different examples of this, mostly due to conservationist reasons. For instance, mountain gorillas have been the subject of programs aimed at monitoring their health in Rwanda, Uganda, and the Democratic Republic of Congo. These initiatives include conducting regular health checks and treating individual gorillas for respiratory infections, parasites, and other diseases.Footnote 12 In Hawaii, monk seals have been treated against hookworm infections, provided medical care when injured or sick, and cleaned of debris.Footnote 13, Footnote 14 In Australia, koalas have been treated against chlamydia, a significant source of suffering to these animals.Footnote 15

Programs targeting parasites or vectors of diseases

Other measures that can protect the health of wild animals have consisted in the nonlethal eradication of certain parasites or of animals that are vectors of diseases. These initiatives do not aim specifically at protecting the health of wild animals but benefit them all the same. One example of this is the screwworm control program. Screwworms are parasite insects that lay their eggs into the wounds of other animals, from which hundreds of larvae emerge that eat the flesh of the parasited animal. Most of the screwworms die young, meaning that they may well have poor levels of well-being. In addition, the suffering they cause can be extremely significant. Infestation has mortality rates between 20% and 80%Footnote 16 and has been reported to be excruciatingly painful by humans who have suffered it. Screwworms have been eradicated in North America, up north from the Darien jungle, using the sterile insect technique (releasing large amounts of sterilized insects).Footnote 17, Footnote 18 The motivation for this was the prevention of economic losses, as screwworms kill a very large number of animals used for food production. However, this measure has also prevented a very significant amount of wild animal suffering.

Animals’ well-being as a key consideration in protecting animal health

The initiatives mentioned above are good examples of the approach prescribed by the One Health paradigm. They also fit the two goals indicated at the introduction. Concern for human health has driven vaccination and parasite-eradication programs, while conservation goals have motivated those focused on providing medical treatment to animals. While both types of measures have benefited animals, it is revealing that helping animals has not been a motivation for their implementation. In line with this, appeals to the One Health paradigm have only rarely acknowledged that animal health matters for animals’ own sake.Footnote 19, Footnote 20 It is not that proponents of the One Health paradigm explicitly state that the well-being of animals does not matter. Rather, what typically happens is that they do not actually address it when defending the paradigm—in most cases, they do not even mention it.Footnote 21, Footnote 22, Footnote 23 Animal health has typically been considered in ways that are merely instrumentally.Footnote 24, Footnote 25, Footnote 26

It could be objected that, strictly speaking, the One Health approach does not imply that protecting animals matters for the animals’ own sake. After all, the premise that human health, animal health, and ecosystem health are interconnected is not really committed to any normative view. It just entails that protecting one requires protecting the others. However, the way the One Health paradigm has been formulated extends beyond this premise alone. The paradigm also aims to optimize each of the three health dimensions it encompasses.Footnote 27, Footnote 28, Footnote 29 This appears to imply that all three dimensions are valued for their own sake.

Moreover, animal health has also been subordinated not only to human interests but also to ecosystem conservation.Footnote 30, Footnote 31 This remains the case even though ecosystem health is, in turn, also often (though not always) subordinated to human health. There are two different ways the appeal to ecosystems in the One Health approach has been understood: in terms of environmental health and ecosystem health. These two concepts are often conflated but are, in fact, quite distinct. Environmental health refers to the ways human health can be affected by various environmental factors, while ecosystem health refers to the functional condition of ecosystems such that they maintain their stability, diversity, and evolutionary and ecological processes over time. Accordingly, when the One Health approach is understood to promote environmental health, the implication is that concern for ecosystems is instrumental for human health. This means that if animal health is considered similarly to environmental health, its use would also be to serve human health. For its part, when One Health is understood as advocating for ecosystem health, the implication is that both human and ecosystem health matter. When this view is supported, animal health is still considered instrumentally, but in this case to both human and ecosystem health. This is reflected in practice: measures that instrumentally modify ecosystems to reduce wild animal suffering are not currently pursued as those that address animal health for ecosystem conservation purposes. This asymmetry becomes even more pronounced in the case of two other paradigms that have been proposed as going beyond the One Health approach: EcoHealth and Planetary Health. These approaches have often been advocated by arguing that ecosystem health at the local and global levels, respectively, is necessary for safeguarding human health.Footnote 32, Footnote 33, Footnote 34 Both EcoHealth and Planetary Health thus place even less emphasis on animal health than the One Health paradigm, as in them animal health is omitted altogether as a distinct consideration,Footnote 35 treating it, at most, as a component of environmental or ecosystem health.Footnote 36

This illustrates the extent to which animal health has been overlooked, since ecosystem health refers to something fundamentally different from human or nonhuman animal health. Strictly speaking, it is not a biomedical concept, but a more abstract and metaphorical one referring to the persistent relations that constitute ecological balance.Footnote 37 In fact, ecosystems are not sentient and on most theories of well-being do not meet the established criteria for being considered subjects of well-being. Yet, the ways the paradigms mentioned above are defended may imply that certain ecosystem features are given moral consideration, while sentient nonhuman animals are not.

This conflicts with the growing concern for the well-being of animals in contemporary societies. Many people today agree that nonhuman animals are sentient beings who can be harmed or benefited by what happens to them and that we should take their interests into account. In many parts of the world, there are laws and initiatives protecting animals that, although very insufficient and flawed, are widely supported by the public. This seems to be the correct attitude to have, as there are very strong reasons to conclude (i) that not only humans but other animals as well are sentient—that is, have experiences that are experienced by them as negative or positive—Footnote 38, Footnote 39, Footnote 40; and (ii) that sentience should be a sufficient—and probably a necessary—criterion for moral consideration.Footnote 41, Footnote 42 The first claim can be defended by arguing that sentience is the best candidate for what makes it possible for a being to be harmed or benefited. This view is supported not only by experientialist theories but also by other accounts of well-being (and ill-being). Any credible objectivist theory should recognize suffering as among the worst things that can happen to someone. Similarly, any plausible desire-satisfaction theory should incorporate this idea—arguably, because ceteris paribus, we typically do not desire suffering to occur.Footnote 43, Footnote 44 The second claim, which links moral consideration to the capacity for well-being, can be supported by accepting that the soundest normative approach is to avoid harming others and to benefit them when possible. If both claims hold, we have reason to treat nonhuman animals as morally considerable beings, independently of any contingent human interests or conservationist goals. No defender of the One Health paradigm would argue that protecting human health should be promoted merely as an instrument for improving animal health, without giving any importance to its value for humans themselves. This would sound rather odd. If the arguments presented above are correct, they challenge the reverse view that does not consider the value of animal health for animals themselves.

How giving animals moral consideration makes a difference

It could be reasonably argued that this discussion has limited practical relevance, given that what ultimately matters are the outcomes of our actions, and if animals benefit from measures inspired by the One Health approach, the underlying motivation may be of secondary importance. This objection is understandable, but it overlooks the fact that adopting an animal-focused approach can significantly influence the types of measures that are ultimately implemented. To start with, concern for the well-being of animals would provide support for expanding current programs improving wild animal health. There are different examples that can illustrate the implications this would have. New medical and vaccination programs could target diseases that have a higher toll for animals (in terms of the suffering and the mortality they cause). Moreover, the scope of already existing and successful programs could be broadened. Consider, for instance, the work that has been done thus far to prevent screwworm infestations in North America. Such work could be prolonged to make all the Americas screwworm free. The Screwworm Free FutureFootnote 45 initiative intends to attain this. This campaign is one that South American governments would be likely to be very much aligned with, due to the heavy economic losses (and sometimes the harm to human health) it would prevent. But it is also one that from the viewpoint of wild animal welfare would be extremely valuable in terms of expected suffering and premature death prevention. In fact, this has been a key concern without which the Screwworm Free Future initiative would not have been launched. For another example, we could consider rabies, which is still prevalent in large areas, especially in Africa and Asia (since wild animal vaccination programs have been implemented in the American and European continents). It has been estimated that around 60,000 human deaths occur every year due to this disease.Footnote 46 There are no similar estimates for the number of animals dying due to it, but we can expect it to be orders of magnitude higher. Given the existing know-how, and the availability of technical means, those figures could be dramatically decreased worldwide if there were a will to invest the resources needed for that. A greater concern for animals could serve as the catalyst needed to make this happen, since anthropocentric motivations alone have failed to do so yet.

In addition, there are interventions we could implement that would significantly benefit animals, but are not currently prioritized due to their limited impact on humans. Many diseases and parasites that affect animals are not zoonotic, yet they can be extremely painful and often fatal. These conditions are usually neglected, except in cases where treatment is motivated by conservation concerns. Examples include sarcoptic mange,Footnote 47 chronic wasting disease in cervids,Footnote 48, Footnote 49 intestinal parasite infestations,Footnote 50, Footnote 51 ranavirus and chytridiomycosis in amphibians,Footnote 52, Footnote 53 white-nose syndrome in bats,Footnote 54 and lungworm infestations,Footnote 55, Footnote 56 among others. Environmental concerns have prompted action in these cases when such diseases threaten conservation goals. It seems that a concern for animals’ well-being would be needed to ensure that these issues are addressed based on the severity of harm they cause. This is especially important, as the diseases that cause the most harm to wild animals may differ from those that may be more important from a human-centered perspective.

Finally, there are also cases where support for these programs may be especially straightforward from a viewpoint focused on the interests of animals because they involve direct conflicts where interventions can either help or harm animals. A prime example is the dilemma of preventing disease transmission between wild and domesticated animal populations by killing wild animals or using wild animal vaccination programs. One conflict of this kind has occurred in the United Kingdom, where authorities faced this choice in the case of badgers that might be infected with tuberculosis.Footnote 57, Footnote 58 In cases such as this, vaccination programs can spare the animals’ lives by protecting them from both anthropogenic and nonanthropogenic harms.

Wild animal welfare science

There is another important implication of caring about animal health out of concern for their well-being. If we care about protecting animals’ health solely to promote anthropocentric or conservationist aims, we need only identify which health-related factors can affect zoonotic risks and how to mitigate them. If, however, we care about animal health for the sake of the animals themselves, then we must learn how these factors relate to what serves the animal’ best interests. This requires understanding what constitutes wild animals’ well-being and how the factors affecting their health have an impact on such well-being. To achieve the best possible understanding of this and to optimize the impact of initiatives safeguarding animals’ health, we need a cross-disciplinary approach that integrates contributions from ecology, zoology, wildlife management, and other fields with the perspective of animal welfare science. Work on this field would involve developing and applying wild animal welfare assessment methods,Footnote 59, Footnote 60, Footnote 61 but also considering, from a broader perspective, how changes in the situation of some animals can affect others positively or negatively (sometimes through quite indirect ripple effects). This field has been referred to as wild animal welfare science or welfare biology.Footnote 62, Footnote 63 Research on it need not start from scratch. An extensive body of scientific literature on the situation of animals in different ecosystems—for instance, on limiting factors, causes of mortality, age-specific mortality, and animal behavior—already provides valuable insights into how their lives and the factors affecting them are, even though they are very rarely focused on the well-being of animals. At any rate, work integrating this knowledge and providing much more detailed insights is necessary, approaching the problems at stake from a perspective focused on the animals’ well-being.

This being said, there are at least two reasons why, in addition to doing research, it would be advisable to also try to make progress implementing measures that can efficiently help animals such as the one we have seen above.

The first one is that to a large extent this is something that has been done extensively already. Initiatives improving the health of wild animals have been run for a long time, and their impact has been well studied. In fact, there are different ways in which both the health of the animals potentially affected by these programs and the impact of such programs are monitored and measured. They include the use of technologies such as GPS tracking, drone surveillance,Footnote 64 advanced imaging and Remote Sensing Technologies like LiDAR (Light Detection and Ranging),Footnote 65 and Biological Sampling Technologies such as the use of environmental DNA (eDNA) sampling from water or soil.Footnote 66, Footnote 67 In addition, the development of new technologies such as the use of artificial intelligence for pattern recognition is also promising in terms of potential future developments in this field.

The second one is that, because the field of wild animal welfare science or welfare biology is new, the number of people working on it and the amount of resources they are able to use is still very reduced. Despite the public support that more work helping wild animals would likely receive, and the incentives that there are to do so for other reasons,Footnote 68, Footnote 69 the development of this field may be much slower than needed. Because of this, promoting the implementation of new programs can not only help animals directly but can also help to accelerate research on the field to provide further knowledge about the impact of such programs. The situation here could be in some respects similar to that of the development of general animal welfare science in the 20th century, which was driven initially not so much by an interest among scientists but by a public demand and the need to inform policies and interventions aimed at improving the situation of farmed animals. Because of this, new initiatives may be crucial to bring more attention to the topic. In particular, identifying measures that can be scaled up can be very important to foster more research on how to implement it and to bring new resources to wild animal welfare science.

The importance of wild animals’ well-being (and ill-being)

The conclusions reached above regarding wild animal health have similar implications for other approaches to preventing wild animal suffering.Footnote 70 This provides yet another reason why advocating for the importance of wild animals’ well-being and suffering in contexts such as discussions of the One Health paradigm is crucial. Doing so can create positive spillover effects by providing support for other ways of reducing wild animal suffering. Fortunately, many initiatives to help animals are already being implemented, including wild animal hospitals, rescues of injured and sick animals, measures to aid animals during extreme weather events and natural disasters, construction of shelters and burrows for wild animals, and programs to improve wild animal welfare in urban and suburban areas.Footnote 71, Footnote 72, Footnote 73, Footnote 74, Footnote 75 These efforts could be enhanced through further work on animal contraception and wild animal welfare assessments.Footnote 76, Footnote 77, Footnote 78 However, these initiatives remain underfunded and underresearched, even though they could be scaled up and expanded just as programs to prevent animal disease. This is important, as there are a number of factors due to which wild animals often suffer and die in addition to disease, such as hostile and changing weather conditions, lack of food and water, different kinds of conflicts, accidents, as well as others that we may fail to notice as they would not affect us, such as changes in the salinity or the humidity of their environments.Footnote 79 Something that can give an idea of how significant the harms animals face due to these factors is that the majority reproduce by having very large numbers of offspring that seldom make it to maturity. In stable populations, on average, only one offspring per parent reaches maturity and reproduces. The remaining offspring die, often shortly after coming into existence, with many of them experiencing very little more than the processes leading to their deaths, which can be rather painful. As a result, many animals may have lives that contain more suffering than pleasure.Footnote 80, Footnote 81, Footnote 82

This is especially significant since sentient wild animals are, by several orders of magnitude, the vast majority of sentient beings on Earth. Their numbers have been estimated to be between 1011 and 1014 for land vertebrates, at least 1013 for marine vertebrates, and more than 1018 for both terrestrial and marine arthropods.Footnote 83 Humans, who at the moment of writing this paper are over 8·109, or vertebrates kept in captivity, who may around 2·1011, are therefore very far from being representative of what a typical sentient being looks like.Footnote 84 Rather, the average sentient being on our planet is a small wild animal that has only recently hatched from an egg. This means that these animals should be taken much more seriously in our decisions affecting them than they typically are. We may consider that a reason against this would be that the majority of these animals are invertebrates whose sentience is more uncertain than that of humans or other large vertebrates. But even if we applied a significant discount rate—counting their interests thousands of times less than those of humans or animals kept in captivity—they would still be extremely significant when considered collectively. In fact, this would remain true even if wild animals’ interests counted for a million times less. This setting aside the fact in the case of some invertebrates like arthropods there are evidences that would suggest that they are indeed sentient,Footnote 85, Footnote 86, Footnote 87 due to which there is a lot of uncertainty about whether—and, if so, how—we should apply such a discount rate. Moreover, even if we just considered vertebrates, and not invertebrates, wild animals would still be vastly more numerous than humans or animals in captivity. In light of this, it looks like the current disregard for their well-being is not based on an adequate pondering of the weight of their interests.

Conclusion

The well-being of wild animals has traditionally been overlooked even in cases where measures helping them significantly have been implemented, such as those protecting their health. In many cases, successfully reducing the suffering these animals undergo may not be feasible until wild animal welfare science is more advanced. However, this need not prevent us from identifying ways in which it is possible to make progress right now. Some of these may involve the development of new initiatives to help animals, while others may just expand effective measures that have been implemented already. The One Health paradigm presents an excellent opportunity of doing this, if implemented while taking wild animal well-being seriously. This can not only make a significant difference for a large number of sentient animals in the near term but can also encourage more research on the issue that can help to foster further work preventing wild animal suffering in the future.

Acknowledgments

Funding for this research was provided by the Spanish Ministry of Science, Innovation and Universities and the EU, as part of the research project PID2022-142980NB-I00/AEI/10.13039/501100011033/FEDER, UE.

References

Notes

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