Friday, February 26, 2016

Animal Doctors, Human Health

By B. Lana Guggenheim, Staff Writer
The history of humans and their animal companions dates back farther than written history has recorded. People have relied on animals for labor and companionship since time immemorial. Dogs are the oldest domesticated animal, co-evolving with humans approximately 27,000 years ago during the Ice Age, functioning primarily as a herding and hunting companion. Cats were domesticated later, approximately 9,500 years ago, about the time of the Neolithic Revolution, in which mankind transitioned from hunting and gathering to farming and settlement building. They served as house companions and pest control, hunting down rodents and insects that threatened grain storage. It is likely that care for these animals alongside their human owners began at this time, primitive though such care might have been.


The earliest written record of veterinary medicine comes from Egypt, 1900 BCE, almost 4000 years ago, and from Vedic literature in India (approximately 250 BCE). The latter contains edicts of the Emperor Ashoka of the Mauryan Empire, where he ordered medicinal herbs planted that were of aid to humans and animals alike. Indeed, after his conversion to Buddhism, Ashoka placed so high a value on animal life that he ended the royal hunt, gave multiple edicts concerning the protection and health of animals, outlawed and fined poaching, and was arguably the first ruler in history to advocate conservation measures for wildlife.
Animal care continued to evolve alongside human society. Horses and cattle often received attention due to their economic significance as beasts of agriculture, as farming aids, means of transportation, and as a source of meat. Farriers in the Middle Ages at around the year 475 would be responsible for both horseshoeing as well as horse-doctoring. By 1356, the Lord Mayor of London, concerned at the poor standard of care given to horses in the city at the time, requested at all farriers within a seven mile radius form a fellowship to regulate and improve their standards of care for the animals, ultimately leading to the establishment of of the Worshipful Company of Farriers, in 1674. The first comprehensive treatise on the anatomy of a non-human species was the Anatomy of a Horse by Carlo Ruini in 1598 in Italy.
By 1783, the Odiham Agricultural Society was founded in England to promote agriculture and industry, and played an important role in the foundation of the veterinary profession as it exists today. In fact, one of its founding members, Thomas Burgess, was the one who began to take up the cause of animal welfare for its own sake. The physician James Clark wrote the treatise Prevention of Disease soon after, in which he argued for the professionalization of the veterinary trade, along with attendant veterinary colleges, an idea finally realized in 1790 by the establishment of the Veterinary College in London. The Royal College of Veterinary Surgeons was established via royal charter in 1844, with veterinary science really coming into its own in the 19th Century both in Europe and the United States. Similar schools were established at this time in Boston, New York, and Philadelphia. In 1879, Iowa Agricultural College became the first land grant college to establish a school of veterinary medicine. 

Contribution to Human Medicine

Since then, medicine for both humans and animals has continued to improve with increased medical understanding, evolution of technology, and standards of care. Indeed, there is much overlap in the standards and practice of medicine between humans and animals. The first two-year curricula in both veterinary and human medical schools are very similar in both course names and content, with differences arising in more advanced and clinical courses. While a graduating veterinarian can enter clinical practice immediately after graduation, most medical doctors must complete an average of 3-5 years post-doctoral residency before practicing medicine independently, and often in a narrow or focused specialty. Post-doctoral residency for veterinarians does exist, but it is comparatively rare. However, this means that veterinarians and medical doctors are uniquely positioned to benefit each other's’ fields, and indeed, veterinarians have contributed to many advancements in human medicine and society.
Veterinarians were the first to produce an anticoagulant that has since been used to treat human heart disease, and developed surgical techniques used in surgery for both humans and animals, such as hip-joint replacement, and limb and organ transplants. In 2011, Dr. Ralph Brinster became the only veterinarian to win the National Medal of Science for developing a reliable in-vitro culture system for early mouse embryos, which is the same method used today for human in-vitro fertilizations, mammalian cloning, and embryonic stem cell therapy. The American Academy of Neurology cites more than 12 neurological diseases and disorders that animal research has helped cure, treat, prevent, or furthered understanding. Research veterinarians are also in the forefront of gene therapies, including cures for two forms of blindness, one of which is now in human trials. 

Infectious Diseases and Bioterrorism

With their background in comparative biology,  veterinarians play important roles in public health, particularly in the prevention of zoonoses, or animal-borne diseases that are infectious to humans. Most diseases are easily shared between animals and humans. Approximately 75% of recently emerging infectious diseases are of animal origins, and about 60% of all human pathogens are likewise zoonotic. Some of the world’s most destructive diseases are vector-borne, which means that they are spread by biting insects like mosquitoes, ticks, and fleas. Some examples include the Zika virus, Lyme disease, and the West Nile Virus. It was veterinarians who were in the forefront of the effort to suppress malaria and yellow fever in the United States. Each year, scientists discover an average of two new mosquito-transmitted viruses. Veterinarians are one of the many groups of scientists that are therefore involved in epidemiology, contributing to our understanding and prevention of disease outbreak.
One example of successful disease prevention occurred in Pennsylvania in 2001, when veterinarians developed surveillance technology that provided the ability to stem an avian flu outbreak, which stopped a potentially devastating epidemic at a cost of $400,000; whilst a similar outbreak occurring simultaneously in Virginia cost the state over $100 million. While avian flu is less harmful to humans than other flu strains, because the disease primarily targets domestic fowl such as chicken and turkey, the devastating economic impact on food production speaks for itself. However, with the rapid mutation rate and high adaptability of the virus, public health officials are concerned that strains may adapt to become more easily transmissible between humans, and therefore more dangerous to human health and the cause of a global pandemic - making cooperation between veterinarians and medical doctors all the more crucial.
Veterinarians have aided gains in other parts of medical science as well. Research veterinarians were at the forefront of numerous pharmacological and pathogenic agent discoveries. They were the first to isolate oncoviruses (cancer causing viruses) in chickens and then mice, the first to isolate Salmonella species, Brucella species, the botulism disease-causing agent, and other pathogenic agents. The understanding of cross-species pathogenic transfer, mutation, and disease manifestation also has its uses in preventing and treating agents of bioterrorism in an increasingly politically unstable and hyper-connected world. 


Because of their work with animals, veterinarians are also deeply involved in food safety and food production and combating the world’s number one public health threat: hunger. Hunger kills more people worldwide than AIDS, tuberculosis, and malaria combined, according to James T. Morris, Executive Director of the UN World Food Program.  In addition to tackling animal diseases, such as avian and swine flu, veterinarians also develop food safety systems. One such system, which debuted in 2011, enabled eggs to be tested for Salmonella at a swift rate - about 10 times faster than previous methods. This not only saved millions of dollars and ensured public safety, it also increased the distribution of food available to the public. Veterinarians working with dairy farms advise farmers on feed formulations and additives, as well as milking schedules. Not only does this aid the animals, it aids the farmers, as it often results in increased milk production. In the USA, milk production has grown even as the number of dairy cows has decreased.
Beyond enabling and encouraging consumers to eat local foods (a benefit to farmers and the environment at large), this has global implications as both First World and developing countries demand higher quality food and more of it, particularly animal proteins such as meat, milk, and eggs. In the developing world, milk production has not grown despite the increase in number of dairy cows - a trend that veterinary science can help reverse - to the benefit of hungry populations worldwide.

From this brief overview, we can see that veterinary science has huge social effect well beyond care given to companion animals. From aiding advances in medical science, to prevention of infectious diseases, to addressing world hunger, veterinary medicine is responsible for the health and well-being of the entire globe, both for humans and the animals we live with.


 Images Courtesy of Shutterstock.


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