Live Animal Laboratories in Physiology Teaching

Murry J. Cohen, M.D.

Physiology animal laboratories, customarily offered in the first or second years of medical school, have long been considered essential to medical education.1 Grouped with other basic sciences, these laboratories are traditionally offered to supplement didactic teaching of physiology with "hands on" experience, measuring physiological responses to various perturbations in dogs or pigs.2,3 Such laboratories are garnering increasing scrutiny because of: 1) their expense; 2) growing students' ethical opposition; and 3) increasing availability of excellent alternatives and/or replacements.4 As suggested some years ago,5 new approaches6,7 to the teaching of basic physiology include innovative methodologies that could substantially alter the way physiology is taught.8

Because medical students are usually eager to experience clinical work early in the curriculum, clinical experience--traditionally included during the second two years--is increasingly assigned to the basic science years. Begun around 1951, the didactic advantage of such an approach over the previous organ-system-based curriculum model has improved task performance when material was taught in the context in which it was used.9 It appeared that learning human physiology in a setting wherein human problems occurred in human patients worked best.

Accordingly, a recent trend in medical education, called problem-based learning (PBL), considers both students' desire for early clinical experience and recent findings in cognitive psychology regarding principles of learning.10 The problem-based curriculum, introduced at McMaster University in Hamilton, Ontario,11 has been in existence since approximately 1971, and is more and more frequently being incorporated into the curricula of U.S. and Canadian medical schools. It has been described as one of the most significant developments in professional education,12 aiming "for efficient acquisition and restructuring of knowledge and demonstrating relevance in context."13

Within the PBL paradigm, students, under the tutelage of a preceptor, learn basic science in small groups in the context of an identified clinical problem. The scientific principles thus learned are experienced by students as relevant to clinical matters, and are therefore better integrated into their general learning experience. PBL involves commitment to lifetime training in medicine, de-emphasis on lectures, emphasis on small-group sessions, early introduction of clinical contact with active learning, and integration of basic science and clinical curricula by clinical problems.14 Purported advantages of problem-based learning include teaching students to be more empathic and holistic,15 and better prepared to apply basic science concepts in clinical settings.16

PBL has become an affirmed means of medical instruction,17 endorsed by the World Health Organization12 and the Association of American Medical Colleges,18 and accepted by students.19

Harvard Medical School has embraced this approach in its New Pathways curriculum, one aspect of which involves supplementing didactic instruction in physiology with an exciting new practicum.20 Small groups of students are present in the cardiac operating room, where, under the tutelage of a preceptor, they observe the sophisticated measurements of physiological responses of patients to different stimuli, including drugs, surgically-imposed trauma, neural stimulation, blood loss, de- and over-hydration, and others. These physiological responses are discussed by the preceptor as they occur in actual human patients.

Another new modality to teach physiology involves interactive computer programs,4 such as SymBioSys.21 Such a program allows students to repeat maneuvers until they are understood, immediately identifying incorrect responses without any risk or loss of life, and without the anxiety that accompanies working on a living organism.

Are such computer simulations effective? In order to evaluate students' acceptance of animal demonstration versus computer simulation in the teaching of cardiovascular physiology at the University of Chicago School of Medicine, Richard Samsel and colleagues polled students' preferences, finding computer simulations rated over animal demonstrations.4 Their conclusion that "At the introductory level, the computer appears to provide an effective alternative"4 resulted in The University of Chicago's discontinuation of live animal labs. After an extensive study of U.S. medical schools, Ronald Carlin reported ". . .the need for change. . ." in the physiology curriculum, and ". . .an urgent need to reevaluate course content, decide the fate of the student laboratory, and develop new, innovative teaching techniques."22 Fawver, Branch, and colleagues compared dog and computer laboratories and found that the latter accomplished the pedagogic aim faster and better.23 Tsang and colleagues, examining non-animal methods in teaching laparoscopic surgery, found no difference in surgical complications between physicians trained in only non-animal methods and other methods.24 Richard Simmonds, vice-president elect for the American Association for Laboratory Animal Science and Director of Laboratory Animal Medicine at the University and Community College System of Nevada, has predicted that animal laboratories will decline in the future and will eventually disappear.20

Although the final word is not in, available evidence suggests that nothing is lost by substituting operating room demonstration and/or computer simulation for animal laboratories. Curricula committees at most medical schools must agree, for these institutions have discontinued them. Most of the top medical schools in the country have completely terminated them, and a minority have made them elective. 69% of all American medical schools have completely eliminated animal labs, and only one still offers a mandatory animal laboratory in the first-year physiology curriculum.25

References

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