Animals and Public Health chapters

Chapter 1. The Welfare of Animals and It’s Relevance to Our Health

Alvin Tarlov, Director of the Texas Institute for Society and Health, explained that ‘there are five major categories of influence on health:

  1. genes and associated biology;
  2. health behaviors, such as dietary habits, tobacco, alcohol and drug use, and physical fitness;
  3. medical care and public health services;
  4. the ecology of all living things;
  5. and social and societal characteristics’.

As stated by Stephen Leeder from the Menzies Centre for Health Policy in New South Wales, Australia, ‘the new public health makes considerable reference to sociological and anthropological insights and engages with the world of human behavior … in pursuit of better health’. As a result of these insights, physicians, nurses and public health practitioners have become an integral part and are, at times, at the forefront of social change. We now understand that how we interact with and treat each other, how we view others, how we share (or do not share) our resources, how we eat, how we work, how we play, how we shelter ourselves, how we think, how we govern ourselves, how we spend money, how we relate to our environment—in short, how we live—influences our health. Despite all that we have come to understand, however, we have yet to fully appreciate one of the major categories described by Tarlov: the ecology of all living things. It is true that we study in great detail the life cycle of mosquitoes and are applying greater attention to environmental changes. But we have always overlooked (with the few exceptions described earlier), and continue to overlook, a significant facet of human existence that has prevailed since our beginning: our relationship with and treatment of other animals.

Today, food security issues, limited health care resources, unsustainable consumption patterns, environmental degradation, bioterrorism, global warming, human population growth, obesity, novel infectious diseases, world hunger and violence are now emerging as the most urgent public health issues that we face. The complexity and multifactorial roots of these issues necessitate a public health strategy that goes well beyond the health sector. We have started to do this. Due to recent and significant changes in our climate, for example, the fields of public health and medicine have begun to acknowledge that how we treat our planet affects our health. To fully tackle these urgent issues head on, we must also acknowledge that many of them are inevitably linked with how we treat other animals. It is overly simplistic and inaccurate to say that every human–animal encounter that is connected with human illness is a result of our actions or is avoidable. Yet, a significant proportion of these connections are, at least in part, a result, directly or indirectly, of our disregard for or minimization of the welfare of animals.

If public health is concerned about the public’s health, then it must address a series of issues that it has so far largely avoided—and that affect the welfare of animals. If public health is concerned with how climate change endangers human health, it should also be concerned about factory farming’s impact on global warming. If public health is concerned about the threat of new and deadly infectious diseases, it should also be concerned about the wildlife trade’s potential to unleash a pandemic worse than HIV/AIDS. If public health is concerned about limited health care resources, it should also be concerned about how a significant portion of our health care dollars is diverted into animal experiments of dubious medical value. If public health is concerned about the alarming rise in antibiotic resistance, it should also be concerned about the ubiquitous feeding of antimicrobials to animals on industrial farms. If public health is concerned about violence, it should also be concerned about the connection between violence toward animals and violence toward people. If public health is concerned about the epidemic of obesity, it should also be concerned about obesity’s connection to our unprecedented consumption of animal products. If public health is concerned about the safety of our food, it should also be concerned about factory farming’s effect not just on the safety of animal food products but also on that of our fruits and vegetables.

In short, if public health is concerned about the protection and promotion of human health, and if public health acknowledges that every other facet of human existence plays a role in our health, it must also acknowledge that how we relate to animals is a major determinant of our health. If public health is concerned about public health, we must turn our attention to the elephant (and every other animal) in the room.

Chapter 2. Victims of Abuse: Making the Connection

The following is a typical case illustrating the linkage between child abuse and animal abuse. One morning, an Atlanta contractor pulled up to a house where he was to perform some work. As he got out of his truck, he heard a dog screaming from the house next door, went over to investigate and saw through an open garage door a dog dragging his back legs and a woman standing beside him. The contractor intervened and took the dog to a veterinarian, whose suspicions about the incident were confirmed. The dog could not be saved and an autopsy revealed that the dog was paralyzed from having been beaten so badly. The incident was reported to the police. When the police went to the woman’s house to make an arrest for abusing the dog, they found a badly bruised boy. Both parents were arrested for child abuse.

Companion animals are increasingly viewed as family members with inherent worth. More than 70 per cent of US households with young children have companion animals. In one study, seven-to-ten-year-old children named on average two companion animals each when listing the ten most important individuals in their lives. When asked ‘Whom do you turn to when you are feeling sad, angry, happy or wanting to share a secret?, nearly half of the five-year-old children in another study mentioned their companion animals. Harm to companion animals can cause tremendous grief and anxiety in those who care for them. Unfortunately, their status as family member renders companion animals vulnerable to abuse, often as a means to exert control and intimidation over other humans. For example, an abusive father may hurt the family dog in order to scare his spouse or children into submission. Threats toward and actual abuse of animals in domestic violence situations occur for a variety of reasons, including:

  1. to confirm power and control over the family;
  2. to perpetuate an environment of violence and fear;
  3. to coerce the victim or prevent him or her from leaving;
  4. to force the victim into silence;
  5. to punish the victim;
  6. to further degrade the victim by forcing his or her participation in animal cruelty acts.

In a survey of 107 battered women, 47 per cent of those with companion animals reported that their abusers threatened or harmed the animals. Additionally, more than half of these women said their companion animals were important sources of emotional support and 40 per cent had delayed seeking shelter out of concern for the animals’ welfare. Once in the shelters, many of the women continued to worry about the animals’ safety. That concern is not unfounded. Several cases reveal the horrific cruelty inflicted on animals by batterers: a pet cockatiel was beheaded because he was ‘singing too much,’ a cat was hung by a leash, another cat was put into a microwave and other animals have been kicked, stabbed, shot or thrown. In another study of battered women, 71 per cent of those with animal companions reported that their partners had been violent to the animals. The women reported that their partners abused animals for revenge or to psychologically control them. Quinlisk reported findings of a survey conducted as part of a domestic violence intervention program. Of the 58 female victims of domestic violence who had companion animals, 68 per cent reported violence directed toward their companion animals. In 88 per cent of cases, the violence was committed in their presence. In 76 per cent of these cases, their children also witnessed the animal cruelty. In other cases, women reported receiving threats either to kill or give away the animals.

Chapter 3. Lions, Tigers and Bears: The Global Trade in Animals

On 20 August 1994, an international uproar was caused by an incident involving a female African elephant who went on a rampage in Honolulu, Hawaii. The animal, Tyke, was ‘performing’ during an event for Circus International when, before hundreds of horrified spectators, she grabbed her trainer, thrashed him about and killed him before turning on her groomer and goring him. She then ran from the arena and escaped to city streets, where for 30 minutes she caused havoc and threatened the public before police shot her almost 100 times. It took her two hours to die.

Why did Tyke, after years of performing for this circus, suddenly turn and attack the two people with whom she had spent most of her circus life? To answer this, it might help to take a look at the life she led up until that fatal day. Tyke’s keeper, John F. Cuneo Jr., owned Hawthorn Corporation, one of the largest suppliers of performing elephants and tigers in the USA. While most of Tyke’s life history with Hawthorn Corp. is not publicly known, that of Lota, another elephant kept by the company, is. In 1952, she was captured from the wild as a baby in India and torn from her family. Lota lived her first two years in captivity in a zoo in India before being shipped to the Milwaukee County Zoo in the USA, where she spent the next 36 years of her life with three other female elephants. At the Milwaukee zoo, the three elephants were routinely chained by two legs to the floor of their barn for at least 18 hours a day. Zoo staff conducted videotaped training sessions for new employees in which the elephants were repeatedly struck by bullhooks.

Over time, Lota became too aggressive for the zoo to handle. In 1990, she was sold for US$1 to Hawthorn Corp. In a widely publicized video, she was shown being beaten and dragged into a trailer as she fought her chains, which finally broke, sending her falling backwards and then sliding beneath the trailer. This video footage caused an international outcry and repeated pleas that the elephant be sent to a sanctuary. Despite the pleas, Hawthorn would not relinquish Lota and she was kept in chains throughout her life, being dragged around and rented out to one venue after another to perform. In 1996, she contracted tuberculosis. In 2001, a US Department of Agriculture (USDA) inspector cited Hawthorn for failure to provide veterinary care to Lota, who was ‘excessively thin, with a protruding spine and hip bones and sunken in eyes’. No improvement in her condition was made, however. Returning later that year, the USDA again noted Lota’s dismal state, reporting that she was in a ‘perilously emaciated state, with a wound on her left hip’. The elephant died from tuberculosis in 2005.

Based on Lota’s experiences, it seems likely that Tyke’s life was similarly wretched under the care of Hawthorn Corp. A report in Nature reveals that elephants, when exposed to violence and psychological and social trauma, can suffer from post-traumatic stress disorder. Could it be that Tyke, after a lifetime of physical and mental suffering, intentionally lashed out and sought revenge upon those who had harmed her? Or was her attack the result of general psychological illness produced by years of confinement, captivity in sterile environments and physical abuse? We will never know why Tyke lashed out, but we do know that Lota’s experiences are by no means an exception. Today, thousands of wild or exotic animals are kept in zoos, circuses, marine amusement parks and private residences. Many are used to supply hunting ranches and game parks around the world. These animals are either caught from the wild or bred in captivity and traded around the globe to ensure an ever-ready supply. This is the global trade in wildlife, and all indications are that our infatuation with exotic and wild animals is coming back to bite us.


The trade is directly and indirectly leading to a rapid rise in new infectious diseases, the spread of existing diseases, injuries in people and the loss of species at a rate never before seen. As we delve deeper into the world’s forests and jungles to capture, kill and collect animals for the trade, we are inviting pathogens never before encountered to jump into the human population and wreak havoc. As we rip animals from their natural habitats, we are disrupting ecosystems in profound and perhaps irreversible ways, which will in turn cause a surge in some very deadly infectious diseases. And, as we ship billions of animals around the globe, we are ensuring that any diseases unleashed by this trade will impact humans everywhere.

Chapter 4. Foul Farms: The State of Animal Agriculture

As disturbing as the wildlife trade is in fostering the development of new infectious diseases, recent events suggest that the biggest and most imminent threat may lie much closer to home. Between 2007 and 2008, farmers in the Philippines noticed that pigs were falling sick and dying by the hundreds for unknown reasons. A subsequent investigation confirmed the presence of porcine reproductive and respiratory disease syndrome, a serious illness among pigs. But, much to the surprise of the investigators, a subtype of Ebola virus, Ebola Reston, was also discovered circulating in a sample of the pigs. This was the first time Ebola of any strain had been found in these animals. ‘We never thought that pigs could be infected’, says Pierre Rollin, an Ebola expert at the Centers for Disease Control and Prevention (CDC).Rollin believes that Ebola Reston is to blame for the pigs’ deaths because tissue studies revealed that the virus had pervaded the spleen, similar to its mode of attack in monkeys.

Ebola Reston is named after the strain that was discovered in monkeys shipped to laboratories in the USA from the Philippines on several occasions between 1989 and 1996. The first shipment of Ebola virus was discovered after hundreds of monkeys became severely ill or died in a quarantine facility owned by Hazleton Laboratories (now Covance, Inc.) in Reston, Virginia. Because this was the first confirmed instance of Ebola entering the USA, a panic swept across American health agencies. All remaining monkeys at the facility were euthanized and the building was eventually demolished. Although evidence revealed that humans were also infected, Ebola Reston proved to cause at worst only a mild flu-like illness in humans, unlike all other known strains of the virus. Thus, Ebola Reston, although deadly in monkeys, was deemed only a minor threat to us. However, new fears are rising since Ebola Reston was discovered in pigs.

The industrialization and mass production of animals for food is now among the biggest contributing factors to emerging infectious diseases over the past few decades. Pigs and other animals raised for food are critical sources of zoonotic pathogens that threaten human health and have been directly implicated in the emergence of the H5Nl avian influenza virus, the 2009 H1N1 ‘swine flu’ pandemic virus, the rise in foodborne infectious diseases, and other significant infectious pathogens and diseases. To understand how and why animal agriculture fosters the emergence of new pathogens, it helps to get a glimpse of the experiences of animals raised on modern ‘farms.’

Humans are consuming more animals than ever before. Once viewed as a luxury, meat is now becoming a dietary staple for many due to a worldwide growth in urbanized populations and affluence. Today, more than 64 billion animals are raised and killed for food worldwide annually. That means that more than nine farmed animals exist for every human at any one time. China and the USA are among the largest farmed animal producers in the world. In the USA alone, an excess of 9 billion land animals are slaughtered annually for food, approximately 1 million per hour. On average, each American eats the equivalent of 21,000 animals in his/her lifetime. And, global meat production is expected to double by 2020. Consequently, over the last half-century, a dramatic shift has taken place in the animal agriculture industry that may represent the most profound change in the relationship between humans and animals since animals were first domesticated.

In the name of efficiency, the industry has chosen to sacrifice the space and well-being of animals. Traditional farming practices in which animals were permitted to roam outdoors prior to slaughter have largely been replaced by immense, intensive animal operations. These concentrated animal-feeding operations (CAFOs) or factory farms changed the status of animals like nothing had before. The industrialized methods of raising animals for food have spread throughout much of the world. The result is that traditional farms in developing nations are being replaced at a rate of more than 4 per cent a year. The independent family farm is rapidly becoming a thing of the past. Today, most animals raised for food are produced by a few immense agribusiness corporations that intensively confine animals by the hundreds or thousands in consolidated operations. This demand-driven transformation of animal agriculture is so dramatic that it has been dubbed the ‘Livestock Revolution.’

Chapter 5. Animal Agriculture: Our Health and Our Environment

Even if we could, no matter how unlikely, contain the pathogens running amok among factory farms, we are still faced with a much larger problem. This is because there are just too many animals being produced for food: animals grown for meat and dairy products account for 20 per cent of the world’s terrestrial animal biomass. To sustain this massive production requires unprecedented quantities of water, energy, land, pesticides and feed crops (crops fed to farmed animals). In exchange for all these depleted resources, we get polluted water, air and land, and perhaps one of the most significant climate transformations in human history.

In September 1999, Hurricane Floyd hit the eastern part of North Carolina, acting as a catalyst for the environmental disaster that followed. As many as 50 animal waste lagoons, some of them several acres in size, filled with floodwaters and overflowed. This manure flowed into the surrounding wetlands and groundwater aquifers, resulting in massive contamination and pollution of drinking water. In addition to multi-antibiotic-resistant fecal bacteria and antibiotics, excess levels of nitrogen nutrients were discovered in the groundwater near some of the farms following the flooding. North Carolina is the second largest pig producer in the USA; pig production in that state alone exploded in the 1990s, growing from 2.6 million pigs in 1988 to almost 10 million today, most of them confined to factory farms. The aftermath of Hurricane Floyd highlighted the disturbing environmental implications of industrial animal agriculture.

In the USA, animal agriculture is responsible for 32 and 33 per cent, respectively, of the nitrogen and phosphorus loads found in freshwater sources. The problem with these nutrients is that, like manure, there are too much of them. The application of manure to cropland and leakage from manure lagoons cause nitrogen, phosphorus and other nutrients to run off agricultural land and into waterways. Excess nutrient loading of waterways causes eutrophication, or overfertilization, leading to loss of oxygen, algal blooms and massive die-offs of fish and other animal populations. Most marine algae are harmless. However, the growth of several toxic species of algae is boosted by nutrient supersaturation. These species produce potent neurotoxins that can be transferred through the food web, where they adversely affect and kill fish, birds, marine mammals and humans that either directly come in contact with or consume them.

One harmful species, Pfiesteria, is believed to be the cause of massive fish kills along the eastern shore of the USA. It produces a potent neurotoxin and an epidermal toxin that have been linked to significant neurological illness and skin lesions in humans. Additionally, nitrogen in manure and liquid waste can contaminate drinking water. These nitrates, which are associated with human health risks, have been identified by the US Environmental Protection Agency (EPA) as the most widespread agricultural contaminant in drinking water wells. Elevated nitrate levels in water can cause severe methemoglobinemia (‘blue baby syndrome’), particularly in infants. This is a frequently fatal condition in which the blood has a reduced capacity to carry oxygen.

Excess nitrates and eutrophication render water unfit for drinking. Compounding the eutrophication of our waterways, animal agriculture also consumes 70 per cent of the freshwater supply and is among the most damaging industries to the earth’s increasingly scarce water resources, contributing significantly to water pollution. According to the EPA, agriculture, is ‘the leading contributor to identified water quality impairments in the nation’s rivers and streams, lakes, ponds, and reservoirs’. In excess of 129,000 miles of streams and rivers and more than 3.2 million acres of lakes have been impaired as a result of agriculture, a significant part due to animal waste and factory farms. The primary pollutants associated with animal waste are nutrients (particularly nitrogen and phosphorus), organic matter, solids and odorous/volatile compounds.

Animal waste also contains pesticides, hormones and, of course, pathogens and antibacterials. Pollutants in animal waste can impact water supplies through several possible pathways, including surface runoff, erosion, spills, direct discharge to surface waters and leaching into soil and groundwater. Atmospheric transport is another major pathway by which nitrogen and other pollutants are deposited back to the land and waterways. More than 80 per cent of ammonia emissions in Europe are generated by animal agriculture. Factory farm waste emits a number of pollutants of concern to human health, including heavy metals, volatile gases, methane, nitrous oxide and hydrogen sulphide.

Chapter 6. The Costs of Animal Experiments

The false-positive and false-negative results of the animal bioassay can be considerable. Ennever and Lave analyzed the data on known human carcinogens with the animal data for cancer predictability. They found a disturbingly large proportion of incorrect predictions, ‘potentially allowing widespread human exposure to misidentified chemicals’. An analysis of the data on 780 chemical agents listed in the International Agency for Research in Cancer database found the positive predictivity of the animal bioassay for a definite or probable human carcinogen to be only around 20 per cent. In addition to placing human lives at risk, the low predictability of this assay is costing us money and wasting time. Each assay requires up to millions of dollars and years of planning. In the meantime, as we continue to rely on this assay, there is a huge backlog of untested chemicals to which we are already exposing ourselves.

Other toxicology and carcinogenicity tests that rely on animals are equally flawed. One study examined the toxicological profiles of rodent and non-rodent (beagles and NHPs) species of 50 compounds. The study found poor correlation of target organ toxicity across species and concluded that ‘simple extrapolation across species is unrealistic’. The study authors called for regulatory agencies to institute an evaluation of tests using animals as predictors of human adverse signs. In 1999 the Health and Environmental Science Institute examined the data on 150 compounds that had produced a variety of toxic effects in people. It found that only 43 per cent of the compounds produced similar effects in mice and rats and 63 per cent did so in other animals. A reviewer of toxicology testing and regulations commented that ‘compelled to act, regulators have chosen animal tests to forecast human cancer risks. To this end, animal data are filtered through a series of preconceived assumptions that are presumed to overcome a host of human/animal differences of biology, exposure, and statistics-differences that in reality are insurmountable.’

Recognizing the immense difficulty in predicting toxicity in one species based on the toxicity data from another is not new. As early as 1978, Fletcher found poor correlation between drug safety tests in animals and subsequent clinical experience with 45 major drugs, including anti-cancer agents, antibiotics, cardiac agents and neurological agents. Fletcher’s survey established that only 25 per cent of the toxic effects observed in animals might be expected to occur in humans. Assessing three decades of data on the subject, toxicologist Ralph Heywood also found that the concordance between animals and humans is only 25 per cent. ‘Toxicology’ he concluded, ‘is a science without a scientific underpinning.’

‘In retrospect,’ Fletcher concluded in his 1978 report, ‘it is a relatively simple matter to determine the correlation between animal and human studies, but prospectively it is difficult to know which particular toxic effects are likely to prove troublesome when it comes to giving the drug to man.’ And that’s the catch: accurately predicting when the animal experimental results are relevant to humans is nearly impossible because of inter-species differences. We can always go (and have often gone) back after clinical trials have been conducted to assess whether the animal experimental results correlated with the clinical results, but retrospective confirmation is not the purported reason for using animals in experimentation. They are intended to predict human results and inform human health care. If we find that the animal experimental results equated with the clinical results, then the research community hails the efficacy of the animal experiments. But when the animal and human results do not match, the proclaimed failure is said to be a result of flaws in experimental design, publication bias or use of young animals for a disease that occurs predominately in elderly humans. Rarely is the use of the animals themselves—not how they are used—questioned.

While most researchers admit the difficulty in extrapolating and applying information obtained from other species to humans, commonly proposed solutions to this colossal obstacle are far from helpful. Neyt et al. suggest that ‘clearly profound differences may exist at the gross, microscopic and genetic level between humans and other mammals, and these differences must be appreciated before extrapolating the results of a given study to human clinical practice.’ Caution in extrapolating data from animals to humans is another common advice given. In fact, ‘appreciation of differences’ and ‘caution’ about extrapolating results from animals to humans is now almost universally expressed in published reports on animal experimental results intended to inform human health.

Yet, in reality, how does one take into account differences in drug metabolism, genetics, expression of diseases, anatomy, behavior, influences of laboratory environments, and species and strain-specific physiologic mechanisms and then discern what is applicable to humans and what is not? There is just no established formula or algorithm to do this. Many scientists have recently acknowledged that modeling human disease in animals is extremely problematic but have still argued for their use, instead, to study basic physiologic mechanisms. But again, if we cannot predetermine what mechanisms in what species and what strain of species and in what caging system and even during what time of day are applicable to humans, then the usefulness of the experiments needs to be questioned.

Chapter 7. The New Public Health

We now have a choice before us. Do we use our knowledge to continue to condemn animals to incalculable harm, in turn jeopardizing our own health, or do we use that knowledge to evolve the practice of public health and improve the welfare of all? Do we continue to ignore the sad plight of animals who are abused, traded, eaten and used for experiments and consequently ignore how their plight affects our own health, or do we use our scientific advances and knowledge to fight against abuse, protect animals and their habitats, clothe ourselves without animal skins and fur, entertain ourselves without debasing animals, and feed ourselves and produce medicines without hurting animals?

We can do all of these things today. In fact, we are at an amazing crossroads in human history. We can largely exist and, even more, exist better without compromising the welfare of animals. Curtailing our harmful practices against animals will significantly reduce a great many of the problems that currently threaten our health and welfare.

How often in life are we given the opportunity to tackle several major obstacles to both our individual and collective health—and deal with the ethical conundrum of our poor treatment of animals—with rather simple solutions? In comparison with so many other obstacles that public health faces, such as poverty, war and social inequities, the improvement of animal welfare is often a relatively easy goal to accomplish. A gesture as simple as choosing one plate of food over another can single-handedly help thwart epidemics, curtail global warming and lengthen our lives—and reduce the number of animals in factory farms. By redirecting our medical resources toward the use and development of human-based tests, we can create far more predictive testing methods and avoid significant harm to animals. Striving to minimize the harms we cause to animals does not require us to abandon our quest to further human health. Rather, our endeavor to improve human health will be substantially advanced by promoting better treatment of animals.