Old Myths Die Hard

Old Myths Die Hard A New View of Animal Research Questions Its Scientific Value II By Dr. Brandon Reines uring the last week of April each year, as predictably as the chirping of robins, the deputy director of the National Institutes of Health sings the praises of animal experimentation. "Virtually every medical innovation of the last century," claims Dr. William F. Raub, "has been based to a significant extent upon the results of animal experimentation." The inspiration for such oratory is the agitation of animal-rights and animal-protection groups, marking the observance of April 21-28 as World Week for Laboratory Animals. Dr. Raub is hardly alone in contending that medical discoveries usually come from animal experiments. In fact, that contention is an article of faith among thousands of animal researchers the world over. Not only scientists but the media and many members of the public, as well, believe that no breakthrough in treatment is possible without experiments on animals. This is due in part to the efforts of special-interest organizations whose sole purpose is the promotion of animal research. For example, the National Association for Biomedical Research (NABR) represents laboratory-animal-use interests, including animal breeders, dealers, and researchers. For many years, NABR spokesmen have utilized lobbying and public-relations techniques to promote the selfserving dogma that current medical science is a result of animal experimentation. A growing number of animal protectionists, nonetheless, are skeptical of Dr. Raub's and NABR's claims. The HSUS laboratory animals department regularly fields calls from members and activists who ask: is it ~I ~ I possible that the usefulness of animal experimentation has been exaggerated? Answering that question accurately has been my occupation for the past several years. The answer is an unqualified "Yes." In fact , animal-research interests have been engaged in a propaganda campaign every bit as vigorous and distorted as that they attribute to animal protectionists. Animal-research interests have consistently taken anecdotal information , "expert" opinion, and selected case studies to construct an allegedly airtight case for the indispensability of animals for medical discovery and testing. However, analysis of the history of modern medical miracles-wonder drugs, hormonal therapies, and surgical procedures-reveals that animal research has often not served a scientific function at all . The primary historical role of animal experimentation is forensic. It is a method of "selling" a favored hypothesis to the medical community and/or the public. Medical breakthroughs almost always have arisen from detective work done by doctors in the context of clinical practice (with patients). In the fields of research The Humane Society News • Summer 1989 the experience with human victims was too convincing to ignore. Researchers convinced doctors to try nitrogen mustard as a therapy by emphasizing its positive effects against certain mouse tumors. These positive results did more to reassure doctors than prove the accuracy of the original hypothesis. That was their value. In studying the history of cancer chemotherapy, heart surgery , and several other areas , it becomes clear that animal ex- :..-.&.---•..;;;;.JE;;;;.•wllll•..•~ that have seen the most spectacular advances and milestones (cardiology, immunology, oncology, neurology, pharmacology, endocrinology, hematology), the role of animal experimentation in advancing progress has been grossly exaggerated. An increasing number of scientists share that view. Dr. Irwin D . J. Bross, former director of biostatistics at Roswell Park Memorial Institute for Cancer Research in Buffalo, New York, maintains that none of the major drugs for the treatment of childhood leukemia was discovered through animal experimentation. He claims that the drugs were actually developed in the clinic by direct observations of human patients. This conclusion seems to contradict the fmdings of scientists such as Dr. C. G. Zubrod, who has written repeatedly that all of the major anti-cancer drugs were discovered by animal experimentation. Based on my historical research, it has become clear that Drs. Zubrod and Bross have been ''talking past each other.'' The apparent contradiction is due to a lack of semantic precision in Dr. Zubrod's published statements. Although his formal claims in the literature imply that the main UNIVERSITY OF WISCONSIN PWR.IM~ATE•lB antileukemic drugs were discovered in animal experiments, in a personal communication, Dr. Zubrod conceded,' 'I guess the role of the animal experiments was to convince the clinicians to allow the tests in man.'' That is a very different conclusion from the one he has championed in print for years-that the drugs were actually discovered by animal experiments. Most of the main drugs for cancer treatment were discovered in human studies and, only later, tested on animals. One of the main anti-leukemic drugs is nitrogen mustard. It became of interest to oncologists when a surgeon treating victims of mustard-gas poisoning showed that it knocked out the white blood cells of those victims. Since leukemia is a proliferation of white blood cells, the surgeon argued, any substance that kills white blood cells should be effective against leukemia. With that rationale, researchers proceeded to test nitrogen mustard on a variety of mouse and rat tumors. The results were mixed; nitrogen mustard was actually ineffective against most of the strains tested. The researchers discounted the largely negative studies because The Humane Society News • Summer 1989 periments are often not even part of the SCientifiC research proceSS . They are a Sales tool used to dramatize hypotheses. Of course, experiments in the modern view of science are supposed to test hypothesesnot dramatize them. If this new perspective is correct, then animal experiments are no more inherently scientific than is an inspirational speech. Consider psychological research for a moment. The most famous experimental psychologist in the world, Harry Harlow , is immortalized for his mother/infant separation experiments utilizing rhesus monkeys . He ostensibly sought to answer the question of whether human infants love their mothers because they provide contact comfort or because they are a source of nourishment. To test various theories emanating from clinical observation, Harlow chose an animal species-the rhesus monkey-that has a highly-developed need to cling to its mother in order to survive. Ethnologists were already well aware that contact comfort is more important for rhesus infants than for human infants. "Anyone who has ever watched an infant monkey cling tightly to its mother as the latter swings through the trees can easily understand why,'' writes Dr. Dallas Pratt. By his choice of experimental 13 ferent animal strains they species, Harlow stacked the Historically, animal retried. Tobacco apologists deck in favor of contact search has been used to marshalled leading laboracomfort as the preferred stimulus. Lo and behold, intory scientists to defend the dramatize scientific accuracy fant rhesus monkeys preferof the rodent data. hypotheses rather than red the cloth surrogate No less a scientist than Dr. discover them. Such a mother to the wire surrogate C. C. Little, the founder of distinction proved little mother equipped with a Jackson Memorial Laboracomfort to research milk nipple . tories in Bar Harbor, Maine, animals such as the dog Regardles of whether or insisted that the negative below, kept in a small findings in rodents were abnot Harlo> had a personal cage on a wire floor. solutely conclusive for man; bias towards the contactthere was no evidence that comfort theory, his expericigarette smoking causes mental de ign itself favored cancer because human a particular result. Rather studies are ''merely statisthan a scientific breakthrough, Harlow's experiment, extremely tical.'' Dr. Little maintained that only animal cruel in its many variations, emerges as experiments could prove that cigarette smoknothing but a dramatic illustration of an old ing causes cancer in humans. By sheer hypothesis. As far as human in- persistence, the American epidemiologist fants are concerned, however, the relative who had already shown that cigarettes cause importance of contact comfort and nursing cancer in man managed to fmd a strain of remains unsettled. Nonetheless, Harlow, mouse whose skin would become cancerous named president of the American Psycho- after painting it with tobacco tars. In deslogical Association, was revered for his peration, Dr. Ernest Wynder appeared on research for decades. national television to hold up the mouse he In case after case, animal experiments are had rendered malignant with cigarette tars. used merely to dramatize a clinical hy- Dr. Wynder's statistician at the time was the pothesis . If one strain does not respond in aforementioned Irwin Bross, who, after witthe "right" way, some other strain surely nessing that demeaning display of scientific will. Given the thousands of possible com- showmanship, developed a profound distrust binations of species, experimental manipula- of animal experiments. tion, and environmental circumstances, someone with a vested interest in a particular result can almost always either cite or produce an experimental fmding that will justify almost any public-health decision- even a dangerous one. In fact, some scientists prefer to base public-health decision on highly-variable animal data, even when reliable data on human exposure is available! For example, on occasion , it is virtually impossible to find an experimental species whose reactions mimic those of the human body. Take the rodentand later beagle- experiments conducted to determine the safety of cigarette smoking. When attempts to develop cancer in rodents through smoking failed, public-health actions against cigarette smoking were stalled for more than a decade. While human population studies had clearly shown that smoking caused cancer in people by 1950, experimenters could not produce cancer in animals . no matter how many dif- Dr. Bross maintains that the dogma that clinical hypotheses must be " proven" by animal experiments dates back to the late nineteenth century. ' 'At that time, the dogma made sense," he asserts. That was the heyday of the germ theory of disease, when it appeared as if all diseases were caused by bacteria (or viruses). The analogy between an animal innoculated with a germ and a human being with a germ disease is pretty straightforward. If they absolutely couldn 't find an animal strain that would contract the disease no matter how many times they infected it, then it wasn 't too likely that the germ caused human disease either, although there were many exceptions even at that early date. In the early I 950s, when I was involved in the cigarettellung-amcer controversy, most scientists still believed in the old nineteenth century dogma known as ''Koch's postulates. '' The postulates just don't have any applicability at all to the noninfectious diseases such as cancer and heart disease. The biochemical differences between human and animal tissues are simply too great. When they started making beagles smoke cigarettes in the late '(f)s, I wrote a letter to the Buffalo Courier pointing out how foolish it was. I'm no animal lover, but it was a real waste of money. The evidence that cigarette smoking caused a kind of cancer in dogs finally convinced most of the skeptics although a few holdouts remain. They still reject the cigarette/ lung-cancer theory because the dogs did not contract the human form of lung cancer. There are still scientists who attribute the discovery that tobacco causes cancer to experiments on beagles. The image of beagles hooked up to smoking machines is certainly indelible, but its dramatic impact should not be confused with its scientific content. Like the earlier rodent studies, the beagle experiments were not performed for scientific but political reasons. Beware of NIH administrators who parrot the old party line that " Virtually every medical advance of the past century arose from animal experimentation. ' ' Look out for the songbirds of NIH and NABR. • Dr. Brandon Reines is associate director of the laboratory animals department of The HSUS and author of Masked Men of Medicine, to be published within the year. The Humane Society News • Summer 1989