The Much Maligned:

Pigs and Their Use in Research

By Crystal Schaeffer, MA Ed., AAVS Outreach Director

AV Magazine Spring 2006, The Much Maligned

Dirty. Stupid. Garbage eaters. Stinky. Tasty. These are all words that some may use to describe the much maligned pig. Sentenced through cultural and societal biases, pigs have been relegated to the human food chain and, thus, are not generally thought of as beings, but rather commodities. As such, many meat-eaters are not capable of recognizing the relationship between the pork chop on their dinner plate and the sentient being from whom it came who is symbolized by much beloved characters like Babe and Wilbur.

Truth be told, research has shown that the pig is the smartest of all domestic animal species, including the dog. Pigs are also clean animals who, when given the chance, will not soil their sleeping and eating areas. And, contrary to popular belief, pigs don’t wallow in mud because they like being filthy but rather as a way to keep cool and protect their skin, much the same way elephants do. Nonetheless, these truths seem to elude societal appreciation, creating an absence of empathy, which is represented in many industrial facets, including the biomedical industry.

The Numbers Don’t Lie

Like other species of animals covered by the Animal Welfare Act, the number of pigs used in research has been on the decline, with over 66,500 pigs used in 2000, down to 54,500 in 2004, the most recent year such data was made available by the U.S. Department of Agriculture (USDA). However, as is demonstrated in the chart on this page, a very disturbing trend is occurring. No doubt further exploiting pigs’ much maligned reputation, the animal research industry is using them in experiments that cause pain and/or distress at a much higher percentage than with other animals. According to USDA data, from 2000 – 2004, at least 60 percent of pigs in research experienced pain and distress. In 2004, this figure reached 67 percent. Only nonhuman primates approached these numbers in 2001, when 55 percent experienced pain and distress. During this time frame, the number of other animals experiencing pain and distress hovered around or were well below 50 percent.

The Research

Due to the pig’s large adult size, a variety of mini- and micro-pigs, who consume fewer resources and require less space, have been ‘created’ by laboratories through genetic manipulation and selective breeding in an effort to meet industry’s high demand for these animals. Pigs are common in a number of different areas of experimentation, including cardiovascular systems and blood dynamics, nutrition, drug and alcohol abuse, general metabolic functions, digestive-related disorders, respiratory diseases, diabetes, kidney and bladder diseases, organ-specific toxicity, dermatology, and neurological studies.

In fact, the pig is such a popular animal model of human disease that over the past three years, the National Institutes of Health (NIH) has granted over $7 million dollars to fund the National Swine Research and Resource Center alone. The Center, which is based at the University of Missouri-Columbia, was founded to specifically address the so-called “impediments to the realization of the full potential of pigs as models of human disease,” and, in an abstract requesting funding, boastfully projected that “150-250 pigs of various ages and genetic mutations” would be housed there for research purposes. The primary investigator also outlined the immense reliance on pig models in research, stating, “The importance of the swine models to biomedical research is documented by the fact that NIH currently invests over $100 million annually in swine-based research projects.” As an added testament to the pig’s popular laboratory status, NIH also gave over $22 thousand to support a “Swine in Biomedical Research” conference in 2004, and the Medical University of South Carolina offers “Swine in Biomedical Research,” a two day advanced training course covering topics ranging from husbandry to welfare to surgery to modeling.

In January, an international research team headed by scientists at the University of Illinois won a $10 million federal grant to outline the complete sequence of the pig genome. Researchers estimate that the completed project will cost $20 million and claim the information gleaned from the study could be used to further the use of pigs in research as well as improve production on factory farms, thereby increasing the pork industry’s financial status. Regarding the potential impact this project will have, USDA Secretary Mike Johanns said, “With more than 61 million pigs in the nation, the sequence of the pig genome will have a significant impact on U.S. agriculture.”

Additional research aiding the pork industry is being conducted at the University of Guelph in Canada where researchers have genetically engineered and trademarked the Environpig, a transgenic pig who absorbs phosphate at a higher rate than normal, lessening the need for supplements and reducing the phosphorus content in waste, a problematic pollution dilemma in hog farming. And in an effort to increase food production, the Johns Hopkins University School of Medicine has expressed interest in genetically engineering pigs so that they have extra ribs, having already conducted base research using mice who were born with four or five additional pairs of ribs and also suffered from abnormal spinal columns and small or absent kidneys.

Not to be outdone by agriculture, the biomedical industry also maximizes its exploitation of pigs, and their usage is vast. For example, at the University of Washington, researchers studying burn injuries are attempting to validate the Duroc pig model of scarring, and received over $182,000 in taxpayer money last year to purposely burn and maim pigs. Not only is burn research using animals terribly invasive and painful, but it is also a wasteful expenditure of funds, especially in light of research being conducted by Dr. Charles Hewitt who has developed bioengineered three-dimensional living human skin, specifically to study burn injuries, at University of Medicine and Dentistry of New Jersey. Juvenile pigs are also used at Thermage in California to study cosmetic procedures geared to improve skin tone and facial laxity.

Other examples of pigs used in research include a cardiovascular study at the Allegheny-Singer Research Institute where scientists are receiving $262,500 annually over the course of several years to administer cocaine to pigs in order to investigate the drug's effect on their hearts; a University of Cincinnati project spending over $289,000 taxpayer dollars to study the swallowing mechanics in infants, despite the obvious anatomical differences between pigs and humans; a project in which newborn and juvenile pigs are subjected to intentional brain injury at the University of Pennsylvania, which received funding approaching $1.2 million over a period of five years; a project aimed at developing a pig model of cystic fibrosis, a uniquely human genetic disease, at the University of Iowa, which received $1.6 million in 2004 alone; and at the University of Washington, although humans and pigs differ anatomically, a project utilizing well over $750,000 of federal funds in which scientists use a pig model to investigate bone regeneration of the mandible.

Pigs are also subjected to research involving organ transplantation, and the federal government funds numerous efforts to develop transgenic pigs whose internal organs may be genetically 'suitable' for implantation in human patients, a process known as xenotransplantation. Much of this research focuses on developing animal organs that will not be rejected by human transplant patients. For example, NIH has given Massachusetts General Hospital nearly $330,000 from 2003-05 to "establish a large animal model of chronic lung rejection." Another project also utilizing pigs in xenotransplantation rejection studies is located at the University of Minnesota which, despite the controversy surrounding animal to human transplants, has received over $1.5 million in funding since 1999.

Other studies, such as that at the University of Minnesota, which received half a million dollars in federal funding from 2000-2003, are utilizing pigs to investigate "the risk posed by persistent porcine viruses, which may escape detection by standard screening methods to become pathogenic in humans following xenotransplantation." The possibility of spreading viruses from one species to another is very real in xenotransplantation and is considered a contentious issue in the debate regarding animal to human transplantation. Cloning is also a controversial topic in the biomedical community, but, nonetheless, in 2003-04, NIH funded a study at a cost of over $580,000 to the University of Pittsburgh where researchers attempted to clone pigs who are genetically modified so that their organs would be less likely to be rejected in human recipients.

Schaeffer, Crystal. (Spring 2006). AV Magazine. Pages 20-22.

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