Abstract

1. I review the One Health approach to public health and veterinary medicine and present three contemporary research projects.

2. One Health is motivated by the maxim that the health and well-being of domestic animals, people, and wildlife are inextricably linked. Many projects focus on mitigating wildlife diseases in ways that help humans or livestock.

3. These projects can benefit the welfare of wild animals by improving the target animals’ health. To maximize wild animal welfare benefits, One Health projects should prioritize targeting common species and particularly prolonged or painful health issues.

Key takeaways

• Although One Health does not optimize for wild animal welfare, it represents a tractable opportunity to expand existing efforts in a beneficial direction.

• One Health researchers seem to care about wildlife health for the sake of wild animals’ welfare, not just because of the ways wildlife health issues affect people.

• Demonstrating that improving wild animal welfare can also benefit public health or livestock health might appeal to people who do not typically prioritize animal welfare.

• Established approaches for wildlife health research are relatively easy to extend to high-priority issues in wild animal welfare.

Introduction to One Health

Health, though not the only determinant of good welfare, is a key component (Mellor and Beausoleil 2015). By replacing feeling sick with feeling healthy, good health improves welfare. For the purposes of this article, when I refer to improvements to wild animal welfare, I mainly refer to improving the health of target animals.

Wildlife health projects are promising avenues for improving wild animal welfare. Many of these projects are designed using the “One Health” approach. The framework views both the human and non-human worlds as morally important and interconnected (Schwabe 1984, Zinsstag et al. 2001). For example, veterinarians swear an oath to use their knowledge for both “the promotion of public health” and “the prevention and relief of animal suffering” (Mackenzie et al. 2013). More specifically, One Health follows the maxim that the health and welfare of animals and people are inextricably linked to each other and to the quality of the environment (Osborn et al. 2009).

One Health has been highly successful relative to other health paradigms (Osofsky and Pongsiri 2018). Historically, wildlife health, livestock health, and human health were treated as separate problems. But solving today’s most complex health problems needs expertise in all three areas (Whitmee et al. 2015). Addressing wildlife health, livestock health, and human health collectively — as part of “One Health” — ultimately yields benefits that can’t be found by addressing each problem individually.

Some leading institutions in the One Health movement include One Health Commission and the One Health Initiative. The CDC also includes “One Health” as an important public health approach. Several large projects also originate from the AVMA-accredited colleges of veterinary medicine.

Existing One Health projects

Removing exclusion fencing

Veterinary cordon fences exclude wild herbivores from rangelands throughout southern Africa to reduce the transmission of foot-and-mouth disease between wild herbivores and livestock (Gadd et al. 2012). Foot-and-mouth disease is nonlethal to livestock, but has painful symptoms. Wild animals typically carry the disease asymptomatically (Young et al. 1972, Vosloo et al. 2007).

Exclusion fencing may degrade wild animals’ quality of life more than foot-and-mouth disease itself. Exclusion fencing fragments home ranges and disrupts migration routes. When their movement is constrained, animals cannot escape from potential harms as easily. As a result, cordoned animals more frequently die from starvation, dehydration, electrocution, and entanglement (Gadd et al. 2012, Lindsey et al. 2012).

The costs of exclusion fencing also permeate the socio-economic climate in Africa (ibid, ibid). Outbreaks of foot-and-mouth disease still occur due to fencing failures or mistakes in the food regulatory chain (Thomson et al. 2018). Meat from exposed livestock cannot be sold (ibid), a burden that is largest for low-income producers (Whitmee et al. 2015).

Exclusion fencing does not eradicate poverty from foot-and-mouth disease, and it creates a number of welfare problems for vast numbers of wild animals. The One Health solutions are two-fold: change the regulations for beef so that the process is more humane for people and livestock (MacKenzie et al. 2013), and dismantle fencing. Deaths by entanglement, electrocution, and exclusion-related starvation and dehydration are reduced, and restoring migratory routes improves animals' abilities to act on their behavioral preferences (Gadd et al. 2012, Mellor and Beausoleil 2015, Allen et al. 2018).

Eradicating tuberculosis

Tuberculosis, a severe bacterial infection of the lungs, circulates among human, livestock, and wildlife hosts. Many low-income countries have not controlled tuberculosis. In Tanzania, for example, as many as 16% of all people have had the disease (Travis et al. 2019), as have 1%-13% of cattle, depending on the region (Katale et al. 2013).

An active One Health project has identified buffalo (Syncerus caffer) as a major disease reservoir (Travis et al. 2019, Roug et al. 2020a) and revealed that habitat loss and intensive cattle grazing in and around natural areas have exacerbated transmission by bringing wild buffalo in more frequent contact with people and domestic animals (Kirksey 2012, Roug et al. 2020b).

Rangeland degradation appears to be an overarching problem contributing to poor health from tuberculosis. Following the One Health approach, reducing habitat loss may be a single-source solution that benefits the quality of life of many people and animals.

Surveilling emerging infectious diseases

“Emerging infectious diseases” is an umbrella term for pathogens that are newly discovered, recently evolved, or occupying new ranges or hosts (Rachowicz et al. 2005, Dazak et al. 2000, Bird and Mazet 2018). Emerging infectious diseases tolerated in one host can become epidemics in others — resulting in extinctions, suffering, or economic damage (Rachowicz et al. 2005, Barrett 2014, Zukai 2014). One Health projects to address this include the establishment of a global disease surveillance system with the capacity to respond to these health threats in real time (Bird and Mazet 2018).

This surveillance network is applied to diseases that primarily affect wild animals. Wild rhinoceroses and giraffes have recently displayed novel ulcerative skin infections. The cause in rhinos is thought to be a roundworm, but for giraffes it remains a mystery (Mutinda et al. 2012, Muneza et al. 2016). Disease monitoring efforts like these are a promising tool for learning more about diseases that primarily affect wild animals.

Uncounted numbers of diseases circulate among different wildlife species, but because of the lack of information on diseases that do not (yet) affect people, we have almost no information on the costs these unmonitored pathogens have for wild animals (Dazak et al. 2000). Understanding disease dynamics helps people stop the spread of wildlife diseases to new populations and intervene to restore good health to wild animals currently burdened by disease.

Future research to improve wild animal welfare

Target the worst diseases

One Health has been used many times to address diseases in wild animals. But in some of these instances, wild animals are merely asymptomatic carriers of these diseases. Pathogens that cause painful and prolonged symptoms in wild animals more significantly decrease their welfare (Beausoleil et al. 2012, Allen et al. 2018).

These diseases should be prioritized. Research that compares the relative severity of emerging infectious diseases — regardless of whether the diseases are transmissible to livestock or people — could be a promising way to apply One Health’s disease surveillance network to address wild animal welfare.

It is also important to increase our capacity to address wildlife health issues so that we can treat the prolonged and painful diseases once we discover them. Wildlife health facilities are also a valuable repository of information about wildlife health issues on the ground (Loyd et al. 2017).  Expanding these facilities helps us understand which diseases are most common or cause the most suffering.

Target common animals

Common species such as urban animals, livestock competitors, and agricultural pests tend to be of minimal conservation concern because of their abundance. But welfare efforts targeting common animals are likely to be most cost effective per capita because interventions can be distributed to vast numbers of individuals.

Pigeons heavily populate human-animal interfaces — areas in the landscape where human and non-human animals cohabitate (Kirksey 2012, Pacini-Ketchabaw and Nxumalo 2015). Because pigeons live in cities, they are vulnerable to avoidable and devastating anthropogenic health problems (Murray et al. 2019).

Targeting common animals like pigeons has strong potential to ameliorate welfare issues due to poor health on a large scale. Citizen science data from New York City pigeons indicate that on average, 165 pigeons annually are poisoned by lead (Cai and Calisi 2016). There is no reason to expect this rate to dissipate with time. It is also a minimum estimate because the data is sourced from one wildlife rehabilitation center. If this rate is reflected in all 33 megacities, then at least 5445 pigeons are poisoned each year globally.

Conclusion

Human, animal, and environmental health are linked. It is essential to address healthcare in wild animals to ensure they have good welfare. Veterinarians and wildlife health scientists who follow the One Health approach care about wildlife health for the sake of wild animals’ welfare, not just because wildlife health issues spill over to people. 

One Health continues to make strides toward building a global healthcare system for people, domestic animals, and wild animals. Though One Health projects tend to focus on implications for livestock and human health, there is potential for expansion into a range of wild animal welfare issues. A maximally beneficial welfare intervention would target common animals and their most prolonged and painful health issues.

One Health represents an unusual example of institutions and funding dedicated to improving wildlife health and engages a wide range of scientists and veterinarians. A wild animal welfare project that demonstrates co-benefits to livestock and people could similarly engage these practitioners by demonstrating that improving the welfare of wild animals is an important, multi-dimensional societal issue.