within medicine (Bynum, 1994). For proponent Claude Bernard these uses were entirely justified, for ‘to learn how man and animals live, we cannot avoid seeing great numbers of them die’ (Bernard, 1957, p. 99).
In London, surgeons and (less commonly) physicians acted as governors for the Veterinary College (established in 1791), ran examinations for students, and were well represented on the student body: 130 surgeons had qualified as vets by 1830. Edward Coleman, principal of the College from 1796 to 1839, was also a surgeon, appointed on the strength of his research on animals and ability to teach farriery. He modelled veterinary education on that of human surgery. Veterinary students were encouraged to attend lectures in the London medical schools, while medical students had the opportunity to attend lectures on veterinary topics. However, little research was undertaken at the College. This drew criticisms from the medical press, which campaigned with disaffected vets for the reform of the school. In 1844, vets displaced doctors in the control of student examinations. Concurrently, reforms in medical education restricted the courses on offer. These shifts enhanced the institutional separation of the professions (A. Woods, 2020, unpublished).
However, as shown by the many reports on animal health issues that appeared in the medical press, doctors retained their interest in this topic, to the extent that veterinary surgeons sometimes accused them of stealing their patients. Doctors also conducted numerous investigations into animal disease pathology and epidemiology. Their infrequent use of the term ‘comparative’ to describe such investigations suggests that they regarded them as part of mainstream medicine. Their aims were to document animal diseases, to describe their analogies with human diseases, and to learn about the nature of disease in general. These investigations featured a remarkable and formerly unrecognized degree of collaboration between doctors and veterinary surgeons. Vets drew doctors’ attentions to interesting cases and outbreaks, facilitated their access to live animals and dead bodies, and offered personal insights based on clinical experience. Less frequently, doctors assisted vets in their animal disease investigations. Grass-roots collaboration between the professions was therefore important to the development of mid-19th-century understandings of human and animal disease (A. Woods, 2020, unpublished).
Medical interest in animals was promoted further by two key scientific developments. First, investigations during the 1830s suggested that glanders in horses, rabies in dogs, and anthrax in animals were causally connected to the equivalent diseases in humans (Wilkinson, 1992). Secondly, there emerged a Romantic or philosophical form of comparative anatomy which suggested that humans and animals were formed on the same general plan. In their efforts to comprehend this plan, doctors compared the anatomy and pathology of the bodies and embryos of multiple animal species (Jacyna, 1984; Hopwood, 2009). Humans and animals were thereby brought together in ways that are usually attributed to Darwinism and the germ theory, 30 years later. This finding reveals that contrary to popular belief, the latter events did not spell a complete break with the past. Rather, they formed part of an ongoing process of making and remaking links between human and animal bodies, and diseases.
Veterinary education emerged later in North America than in Europe. While some of the earliest qualified vets were European émigrés, physicians were also extremely active. In the period 1820–1870 they investigated and reported on livestock diseases, campaigned for veterinary education, and established and taught at early veterinary schools that were mostly short lived (Smithcors, 1959). In 1863, Scottish vet Duncan McEachran founded the Montreal Veterinary College. Believing that veterinary medicine was a branch of human medicine, he modelled teaching on that of the McGill medical school. One of his best known collaborators was William Osler, a former student of Virchow’s and lecturer in medicine at McGill, 1874–1884. Osler taught veterinary students, undertook research (mostly unpublished) into diseases of animals, and asserted the value of comparative medicine to medical audiences. Although today he is often heralded as a figurehead of One Health, he was not unusual at the time. His predecessors and successors at McGill also taught veterinary students, and several, such as J.G. Adami, produced more extensive and significant research in comparative medicine (Teigen, 1984, 1988).
Following the 1859 publication of Darwin’s Origin of the Species which claimed that all living organisms descended by evolution from a common ancestor, some doctors attempted to trace the evolutionary history of disease by examining its manifestations in different animal species. The most famous participant was Eli Metchnikoff, whose Nobel Prize-winning theory of phagocytosis was inspired by evolutionary thinking (Tauber, 1994). Animal diseases were also important in the development of germ theories of disease. In Britain, their acceptance was precipitated by the devastating 1865–1867 epidemic of cattle plague, whose pathology and epidemiology was subjected to scientific investigation by medical doctors (Worboys, 1991). Elsewhere, seminal research on germs focused on the nature, prevention and spread of animal diseases. In France, Louis Pasteur produced vaccines against chicken cholera, anthrax and rabies. His German counterpart Robert Koch investigated anthrax and tuberculosis, as well as tropical animal diseases which inspired his concept of the carrier state.
Vets made important contributions to all these investigations, which used a myriad of animals for the purposes of research, diagnosis and the production of vaccines and sera (Bynum, 1990; Wilkinson, 1992; Gradmann, 2010). Existing aetiological connections between human and animal diseases were redefined in terms of germs. A new category of diseases, the zoonoses, emerged to incorporate these and parasitic diseases like trichinosis, for which the life cycle and spread via the meat trade were worked out from the mid-1850s to the 1870s by Virchow, among others. They formed the focus of a new field of veterinary public health (VPH).
Today, Darwinism, the discovery of germs, and the rise of bacteriology, are heralded as key events in the development of One Health approaches. Closer scrutiny, however, suggests that these events had the reverse effect. In redefining disease as the straightforward product of infectious agents invading susceptible bodies, they downgraded the importance of the environment to health (Worboys, 2000). In bringing human and animal biology closer together, they heralded changes – described below – in the epistemic status of experimental animals, from representatives of particular species to ‘model’ humans. In inspiring the mainstream adoption of the term ‘comparative pathology’, they marked the compartmentalization of animal disease from mainstream medicine, while the emergence of VPH resulted in a newly competitive relationship between doctors and vets over control of zoonotic diseases (Hardy, 2002; Waddington, 2006).
Medical and veterinary perspectives on zoonoses often differed because doctors prioritized human health, and vets prioritized health of animals and agriculture. In 1901 Robert Koch famously reversed his earlier opinion that human and bovine tuberculosis were not alike, adding to a climate of uncertainty about the nature, extent, or even existence of transmission pathways. Doctors and vets clashed over the health threats posed by meat and milk, the regulation of these foodstuffs, and how to define a healthy animal. The stakes were raised by Western governments’ growing assumption of responsibility for health, and their increasing reliance
