The Physicians Committee for Responsible Medicine (PCRM) is a fringe animal rights group consisting of an unknown but miniscule number of physicians. They are closely associated with PeTA (office proximity and funding), and, predictably, promote both their self-serving view of the moral and health benefits of vegetarianism while falsely claiming that the consumption of meat is both immoral and a health risk. This is, like PeTA, a group well practiced in the art of propaganda and it's public statements range from being very subtle and nuanced representations of truths and partial truths to being grossly wrong. The catchy name of the group suggests it is mainstream, but it is not (see this and this.)
Predictably, the PCRM and other AR groups oppose the use of whole animals in biomedical research, while promoting "alternative" research methods such as computer modeling, in vitro techniques like tissue and organ culture, and epidemiological studies, typically arguing or implying that a) whole animal experiments are by definition cruel and therefore immoral, b) whole animal studies are unnecessary, and c) whole animal studies actually hinder real progress towards the eradication of disease because the results of animal experiments cannot confidently be extrapolated to humans.
Such claims are totally disingenuous, and I'll address the idea of "non-animal alternatives" as substitutes for whole animal use today. But before I do, I'd like to just point out that tissue culture is not a "non-animal" technique: the cells are from animals, and the typical media in which the cells are grown is calf serum, which is a clearish fluid derived from blood. When AR groups support tissue culture, they are in fact arguing that draining animals of their blood and separating serum from it to feed cells is a moral act. So much for consistency.
In any event, first look at the PCRM's subtle approach to the issue of using animals in experiments. By listing a variety "alternatives" and waxing about their undeniable value, the PCRM author is hoping that the uncanny reader will conclude that because so many wonderful non-animal techniques are available, the use of animals is superfluous for major biomedical advancement.
The approach gets full marks for distraction, but its logic is fatally flawed: it's like saying that because your car has an engine, gas, a transmission and a driver, it doesn't need tires. Yeah - you could probably get your car out of the driveway, but you wouldn't get very far beyond that. The fact that there are many different useful approaches in science doesn't mean that any one is a substitute for another, or that any one can be discarded with impunity.
The point is that clinical studies, in vitro studies, epidemiological studies, computer modeling, etc. all have their place, but neither singly nor in combination are they substitutes for the use of animals any more than the use of whole animals alone could be an adequate substitute for any other approach under all circumstances.
There a couple of kinds of studies that do require the use of animals. One of these is the study of interacting systems: how do the nervous system and the muscular system work to protect, for example, the knee joint from injury, and the consequent disease (osteoarthritis), caused by movement beyond the joint's normal range of excursion? To get at this question, you need to alter the nervous system (for example, you could cut the sensory nerves supplying a limb, and see if the joint develops osteoarthritis - thus the interacting systems) and evaluate the effects on the joint.
Incidentally, this particular question is clinically important because it suggests a new cause of osteoarthritis, a cause that could not be treated by the kinds of pharmacological agents that are presently being developed to act on the tissues of the joint (if the changes to these tissues are secondary to a problem with coordinated muscular activity, then attempts at fixing the joint tissues will be doomed until the underlying neuromuscular defect is fixed).
This is but one example - there are many others, in which only whole animal studies can provide crucial information - like improved methods for diagnosing and treating heart attacks, the effects of shock wave treatment for kidney stones on kidney function, how bone heals, how to improve brain recovery after stroke, etc.
Another kind of study has to do with birth defects. It turns out that a developing fetus is incompletely separated from the mother's blood supply by something called the "placental barrier." Some substances can pass across this barrier, and some cannot. Some that pass through are good for the fetus (as in nutritive) some are not (as in they can cause birth defects). And some substances have no effect on the fetus. The only way to identify which substances are toxic and which are not is to try them out on pregnant animals, because the only important end point of the study is whether or not the substance caused birth defects to occur, or caused an increase in fetal death. And for this endpoint to be identified, the pregnancy must go almost to term.
Finally, there is the teaching of surgical techniques. Now, most medical students don't learn very much technique at all while in medical school. If they elect to become surgeons, they learn most of their skills incrementally, under close supervision, on human patients. And this is as it should be.
But there are subspecialties of surgery that require far more precision than general surgery, and the people who enter these areas become expert at sewing together vessels and nerves that are only a few millimeters in diameter. These are the microsurgeons, and different subspecialists do things like plastic surgery, or reattaching scalps or severed fingers, or operating on the tiny hearts of infants.
Microsurgeons learn their craft on rats and rabbits. Classically, under anaesthesia, a rabbit's ear is severed at about its midpoint, and then the surgeon reattaches it under magnification using specialized instruments. In another exercise, the surgeon will anesthetize a rat, and cut a nerve in the back of the thigh (the sciatic nerve) and then suture it together.
Here, the appearance of the suture line and the beauty of the healing by themselves are irrelevant. What is relevant is whether or not the repair was accompanied by the return of function, and the only way function can be determined is to follow a living animal after the procedure for days. How adequate is the blood supply? Are the nerve's motor and sensory functions recovering as hoped? Obviously, the requirement for a functional end-point, as opposed to a structural one, rules out the use of cadavers, and until a surgeon can consistently achieve good function, he ought not to operate on human beings (ooops - there's the judgmental "specist" in me ...).
So - keep some of this in mind when you hear that the use of whole animals in research isn't necessary.
Brian