Thursday, January 31, 2008

Evolution in medicine

A small example of the self critical nature of science based veterinary medicne

ResearchBlogging.orgThis recent retrospective case series1 reviews the relatively common and widespread use of a particular steroid- dexamethasone- for acute spinal intervertebral disk herniation in dogs. Though it’s not a huge study, it is well done and helps shed a little more light on whether this old stand by therapy is really worth using.

And that’s what makes this review particularly interesting. It reflects a common characteristic of science based research that you do not often observe in alternative medicine- to question the use of an old assumed to be effective therapy- and find it wanting. How many times do you see that in CAM research?

The use of high dose steroids in primary (i.e; compression, trauma, contusion) and secondary (i.e.; inflammation, vascular ischemia) spinal cord injuries has been in practice since the 1960’s. With the huge expansion of excellent tertiary care facilities and increased availability of board certified surgeons, the role of decompressive surgery is becoming a far more common treatment of choice for primary injuries in veterinary medicine.

On the other hand, the management of secondary spinal injuries in dogs- and humans to some extent- still involves using therapies such as high dose steroids. The underlying rational here has been based more on the merit of a plausible physiological mechanism than any solid proof of efficacy. Reviews like this one help add to the rather scant evidence of what really happens. It is important to note that some alternative therapies being used base their rational on similar levels of plausibility- yet they seem to avoid (or ignore) similar levels of scrutiny as seen here.

The assumption regarding steroidal therapy, in this case dexamethasone, has been that they contribute to neuronal protection by reducing spinal swelling, minimizing oxidative processes, improving blood flow, and reducing damaging chemical mediators. This review indicates that the existing studies out there actually seem to show a mixed bag of effects and, that on balance, it behooves the practitioner to think twice about high dose steroid use, particularly dexamethasone.

The review looked at 161 dogs and grouped them according to steroid use or no steroid use. After accounting for a variety of confounding factors (i.e.; age, sex, hospital, length of hospitalization, cost, blood values) the authors came up with results that do not support the use of high dose dexamethasone as compared to no steroid use (and to a lesser degree other steroids).

Essentially the side effects, which included vomiting, diarrhea, and urinary tract infections where significantly higher in the dexamethasone/steroid groups than the no use group. In addition, the observed benefits (neurological improvement) from using dexamethasone were not significantly different than those in the no treatment group. In other words, there were more side effects than benefits from this type of steroid administration.

The authors conclude that high dose steroid use for secondary spinal injury is not as clearly effective as theoretical physiological mechanisms would indicate and care should be taken when considering them for secondary spinal injuries. It does not necessarily cut dexamethasone completely off the treatment list, but highlights more clearly the problems for clinicians who are considering using it and suggests that timing of administration, lower dosages, and maybe other steroids may have a better impact and reduce negative effects. The authors caution that due to the retrospective nature of the review, there could be substantial variability in time and duration of treatment with dexamthasone and bias in examiner assessments "fuzzying" the observations somewhat. Even so, this study is well put together and adds -along with other studies- helpful insight and a more nuanced understanding of actual steroid effects under these circumstances.

From a broader perspective the take home message here is that science based therapeutic modalities are, for the most part, continually going back and questioning even well established clinical modalities in an attempt to improve on the existing knowledge base searching the clues and looking for the best answers whether they support the subject in question or not.

This is in contrast to CAVM where the same clinical modalities (and fundamentally implausible paradigms) continue to be utilized in spite of scant evidence. More often than not, little is ever changed (or disregarded) even when they are repeatedly demonstrated as being ineffective.


1) Levin, LM, Gwendolyn LJ, et al. Adverse effects and outcome associated with dexamethasone administration in dogs with acute thoracolumbar intervertebral disk herniation: 161 (2000-2006). JAVMA, Vol232, No3, February 1, 2008. 411-417

79th Skeptic's Circle

Wanderingprimate gets his own lolcat!

Check out the rest at podblack...great job of skeptical hosting.

Wednesday, January 30, 2008

Complementary and alternative veterinary medicine and vet schools- the darkening (part 2)

The problem with pretending

Today our clinic received some rather disconcerting news. The local specialty veterinary hospital will be sponsoring a visit by a veterinary behavioral consultant. This, in and of itself is no big deal- on the contrary. Veterinary medicine is in need of more professionally trained doctors in this important and somewhat neglected specialty. The degree of dissonance between what a human assumes and the natural behavior of their beloved pets are often at odds. The right kind of advice can be an eye opening and gratifying experience amplifying the wondrous human/animal bond and be a life saver –literally- for some.

However, what concerned us in this case were the other specialties this fine consultant professes to specialize in- acupuncture and chiropractic. Indeed, this is an even larger and more insidious dissonance than animal/human behaviors “gone bad”. It reflects a deepening problem in veterinary medicine.

It’s not so much that a person can somehow include paradoxical ontologies in their head- being scientifically trained yet at the same time dole out non-science without skipping a beat. That is an unfortunate but common malady.

There is a deeper and more pervasive problem here. It is that a specialty hospital is endorsing this doctor, and by default –whether they realize it or not- Complementary and Alternative Veterinary Medicine (CAVM)1 giving it rubber stamp approval. This is a looming problem in medicine of any kind because it mixes non-science with science in a bastardization known as “integrative medicine”.

The public and even generalist veterinarians with their busy schedules may put more weight on this kind of endorsement than is deserved. They, like the specialty hospital might not have paused for a moment to ask important questions regarding the current evidence base for acupuncture and chiropractic. Nor for that matter, would they have delved into the nuances of the placebo effect, the natural history of disease2, or the history of medicine. There may be, as in this particular case, a tacit approval from the local veterinary college adding to the veneer of legitimacy. Given these endorsements- who would spend the time and energy to put out a skeptical voice?

It seems little thought is given to the implications of accepting this integration of science with non-science. It doesn’t seem to occur to people that many “integrative” veterinarians tend to fluidly combine therapeutic modalities in unique and difficult to repeat ways. It isn’t uncommon to find them practicing in a “because it works for me” paradigm where well known and accepted methods of practicing medicine are fused together with an assorted jumble of acupuncture, good advice, and/or some type of nutritional support or therapy with the goal to, for example, attain some imagined “synergistic” effect.

The bottom line is that this type of medicine crosses a line. It goes beyond accepted standards by taking an experimental/experiential approach to medicine to extremes- not relying on the method of science for authentication. It is reminiscent of a postmodernist philosophy where delusions of “relativeness” coalesce with flatly wrong interpretations of reality. It is a realm where undetectable energies exist everywhere and a plethora of “dysfunctions” inhabit imaginary maladies- it is a belief paradigm.

To be clear, beliefs have a place in a socio-cultural context and might be helpful for some practitioners. There is room for these issues in the realm of evidenced based medicine when you take into account the three spheres of influence (practitioner experience/"bedside manner" , client/patient needs, and current best evidence).

One can believe whatever one wants to. On the other hand, when it comes to medicine these beliefs take a back seat and are subservient to evidence, plausibility, and reality. Practicing non-science based modalities in this context makes little sense. This is the problem with pretending.

Just because everyone is doing it doesn’t make it right

The sad thing about these scenarios; where pseudo-science -almost under the radar- becomes “integrated” and accepted into mainstream consciousness, is that it represents a step backward in medical progress.

Based on its relative success (due to genuine interest & some veterinary apathy) with the public, CAVM has also been steadfastly calling for a place at the table of accepted practice. In this regard, the foothold CAVM has attained in academia is a sign of its success.

Unfortunately, there is an even larger form of dissonance occurring at these levels than the previously described instances. Just how CAVM has begun to infiltrate the mostly science based realm of veterinary medicine probably involves a complex interplay between educational issues, funding needs, political pressures, history, and public demand to name some.

For example, anecdotally some in academia have noted that college students seem to have a lack of fundamental critical thinking tools and are therefore less well equipped to handle an important exptectation in university level academics- learning how to "think on ones feet". Add to this the caveat that state funding for school budgets has been decreasing thus increasing the pressure to get it where you can – to follow the money so to speak. This is a recipe for disaster.

As a result, graduate schools may be bending to the wants and whims of incoming classes more than ever before which may affect the type of educational curriculum that is offered. This would include catering more to applying students (and their tuition) which means –according to one academic voice- giving them more of what they want rather than what they need- not good in a credulous society.3

The following quotes highlight the seriousness of these deeper problems. It is not a huge leap to realize how the veterinary profession can be negatively impacted as a result.

"A number of reports in the past several years have raised serious concern about America’s ability to compete with the rest of the world going forward, particularly in science and technology. Sadly, as with the issue of greenhouse gases, this problem will get worse before it gets better. If we begin today, it will take us nearly a generation to develop the needed scientists, engineers and mathematicians. The children currently in U.S. schools are performing badly when measured against children in other industrialized nations, so our pipeline has slowed to a trickle. Children in elementary school must first catch the excitement of science and mathematics, and by middle school, be ready to do well in algebra, in order to be on track to take more advanced mathematics and science courses in high school."

Elisabeth Muhlenfeld, President, Sweet Briar College

"One cannot be a fully engaged citizen in this or any other democratic society without having at least a basic familiarity with the scientific thinking related to such subjects as global climate change, community health, and technology."

Brian Rosenberg, President, Macalester College

"Several recent reports from the National Academies, notably “The Gathering Storm” and “Beyond Bias and Barriers”, have highlighted the increasing dangers facing U.S. science. Our national science efforts are perceived as less and less relevant to America’s youth, and careers in science, technology and engineering are not attracting our most talented."

Phoebe Leboy, President, Association for Women in Science

Whatever the reasons for CAVM’s successful inroads into academic colleges it needs to be made clear that they are gaining ground in areas that imply an acceptance into the mainstream it has not earned and this is a profound development.

Defenders of CAVM often take on a “tu quoque” (you did it too) position claiming that much of “evidence based medicine” is in fact not evidenced based and that CAVM could comfortably fit into this area of veterinary practice and education. This reasoning is based on false assumptions and leads to a slippery slope because CAVM is composed of a spectrum of practices that include marginally plausible (some herbs) to completely implausible (homeopathy, chiropractic) therapies.

These modalities are not being taught as interesting socio-cultural phenomena in a philosophy of science class. They are –one way or another- being stitched into the fabric of everyday academic practice and consciousness.

That CAVM is, for the most part, fundamentally incompatible with evidence- based veterinary medicine seems to go unnoticed. This is a dangerous trend for reason and science and will hurt veterinary medicine in the long run.


1) Or whatever you want to call it.

2) A good review of these issues can be found in the wisdom of Oliver Wendel Holmes:

Suppose, then, a physician who has a hundred patients prescribes to each of them pills made of some entirely inert substance, as starch, for instance. Ninety of them get well, or if he chooses to use such language, he cures ninety of them. It is evident, according to the doctrine of chances, that there must be a considerable number of coincidences between the relief of the patient and the administration of the remedy. It is altogether probable that there will happen two or three very striking coincidences out of the whole ninety cases, in which it would seem evident that the medicine produced the relief, though it had, as we assumed, nothing to do with it. Now. suppose that the physician publishes these cases, will they not have a plausible appearance of proving that which, as we granted at the outset, was entirely false? Suppose that instead of pills of starch he employs microscopic sugarplums, with the five million billion trillionth part of a suspicion of aconite or pulsatilla, and then publishes his successful cases, through the leaden lips of the press, or the living ones of his female acquaintances,-does that make the impression a less erroneous one? But so it is that in Homoeopathic works and journals and gossip one can never, or next to never, find anything but successful cases, which might do very well as a proof of superior skill, did it not prove as much for the swindling advertisers whose certificates disgrace so many of our newspapers. How long will it take mankind to learn that while they listen to "the speaking hundreds and units, who make the world ring" with the pretended triumphs they have witnessed, the "dumb millions" of deluded and injured victims are paying the daily forfeit of their misplaced confidence!”

3) Also in some cases, the onus to comply with the wishes of large donors may play some role in the development of accepting non-science and unproven modalities so uncritically into veterinary teaching hospitals.

Tuesday, January 29, 2008

Shiva’s dance

through the curtain of consciousness

In a fascinating conversation with Susan Blackmore, the renowned neuroscientist Vilayanur Ramachandran (Professor of Neurosciences and Psychology and Director of the Center for Brain and Cognition at the University of California, San Diego) notes that our conscious existence is “…like the whole dance of Shiva thing, that you think you are an aloof spectator watching the universe, but actually you’re just a part of the cosmic ebb and flow of the world…” That is, we are not separate entities from our bodies- no immaterial soul that can float away from the functional machinations of the brain.

A decade ago, it may have been strange to hear a scientist talk so boldly about what heretofore has been the strict realm of the metaphysical meanderings of philosophy and religion. This is because, until now, the mysterious happenings behind the veil of how our brain functions including the question of the “self” - what consciousness is- have been unanswerable dilemmas.

Stanislas Dehaene aptly describes the brain as “the outcome of five hundred million years of tinkering. It consists in millions of distinct pieces, each evolved to solve a distinct yet important problem for our survival. Its overall properties result from an unlikely combination of thousands of receptor types, ad-hoc molecular mechanisms, a great variety of categories of neurons and, above all, a million billion connections criss-crossing the white matter in all directions.”

In spite of this incredible complexity and the challenge it brings, our understanding of brain function is getting better as neuroscientists manage to peer deep into the minds inner workings gathering significant- and rapidly growing- empirical evidence of actual brain function.

For example, one of Ramachandrans early experiments using a stereogram shed light on how the brain processes perception and merges it with conscious awareness. He inputed separate images in each eye of an observer and found that even if their eyes processed an image in two different ways an internal “stereomechanism” extracted and congealed the information in such a way that the brain consciously saw not individual images, but one in full stereo.

This hinted at how the brain creates mechanisms for efficiently gathering and presenting data into a flexible “package” or self in order to react appropriately to given sensory inputs. In humans, this ability has been taken to breathtaking new levels of flexibility creating, he claims, a unique phenomenon- human consciousness.

In essence, ones “self” can not be separated from the “qualia” or experience1 and no real separation between an “outer and inner” world really exists (this is where dualists disagree). However, the human brain seems to have an added capacity (as compared to other animals) to take these events and examine them recursively- this is the core of experiencing an event as yourself with the “feeling” of you. Ramachandran calls this added layer of analytic capacity a second parasitic brain or meta-awareness. It is not some separate ephemeris soul-like quality but an integral part of the brain.

The human ability to blend sensory experience with this added layer of “capacity” where it can be twisted and turned in a virtual environment is not a redundant computational loop- it actually forms a critical key to thinking.

Ramachandran notes “you’re doing it to fulfill a computational need, namely open ended symbol manipulation in your head. This is what we call thinking: coming up with outlandish conjectures which are made by the imagination, by juggling these symbols in your head. And closely linked to that is the emergence of language: being able to communicate these ideas, intentions, and thoughts with other people; and constructing a theory of other minds.”

These uniquely human traits stem from whatever evolutionary pressures occurred that created a need for this computational hat trick- to create a representation of a representation- to for example enable complex social interaction and cooperation. Part of the emergence of “self” could be due to a kind of “spatio-temporal smearing” as our brains create innumerable inferences from perception (think) and this could cause a sense of internal being.

This construct of how our brains integrate information resembles the Baysean Brain. Here the functions of meta-representation form part of the brains ability to perform according to Dehaens “optimal inferences and make optimal decisions based on the rules of probabilistic logic.”

In other words, the brain elaborates a mental “3-D picture” of the real world- plays with it in all kinds of ways (i.e.; stretching it , turning it inside out, imagining what its like to be in someone else’s shoes…) and finally comes up with -what it thinks- is the best way to respond to that real world. This phenomenon as a whole might be the key to the feeling of "self".

It becomes evident, based on these observations that our “self” seems to be part of an organic phenomenon intimately tied to the whirling activities of innumerable neurons and brain centers. In essence, it may be that our sense of "self" –that consciousness of being- is a temporal and spatial illusion, a “confabulation”, or a post-hoc rationalization.

This realization –if true- would not make life any less wondrous; on the contrary. As Ramachandran notes “It’s ennobling, rather than diminishing… You’re part of this grand scheme of things.” Indeed, poetically speaking our minds are like ghostly, delicately weaved curtains blowing in a cosmic wind that the universe - like a dancing "Shiva"- gently grasps and takes along as it breezes past.

NOTE: Listen to Dr Ramachandran discuss the mind in an illuminating lecture "A journey to the center of your mind".

1)Ramachandran notes that the self and qualia are like two sides of the same coin, or better like a mobius strip. The two sides are just really manifestations of the same phenomenon.


Blackmore, S. Conversations on consciousness. Oxford university press. Oxford, NY. 186-197. 2006

Monday, January 28, 2008

Complementary and alternative veterinary medicine and vet schools- the darkening (part 1)

The beginnings of an anti-enlightenment era?

Over the past several years, there has been a resurgence of intuitive and subjective practices in the world of veterinary medicine that seems to have paralleled what has been going on in the human realm. Many of the posts on this small blog have, in some way or another, repeatedly lamented the slow insidious dilution of reason that pops up in many places in the world of medicine.

To some, this might seem like a broken record and they may be right. I might touch on some particular pseudo-medical related topic and discuss some of the crucial issues that make them disturbing themes. Through it all though, there is a continual thread of discussion that belies a very basic need medical practitioners and patients need to exercise.

It is simply that critical thought and reason are irreplaceable tools without which the allure of “crank” science and belief based medicine -along with the dangers they pose- would quickly begin to overwhelm whatever truth we have thus far managed to eek out over the last one hundred years.

At times, this is indeed a theme that tends to go around in circles. The same old thing again and again, one dubious practice after another all sharing the same neglect towards critical evaluation while bathing in self deception. On the other hand, because of this very problem, it is necessary work to combat this at a time- ever more so today- when there seems to be a slide back into the slime of pre-enlightenment medicine; a place of increasing delusion where snake oil and charlatans all have equal say with real medicine and effective care is drowned in a sea of anarchic turbulence.

In an effort to grasp just how bad things might be, it is important to gauge to what degree this creeping anarchy (better known as CAM and CAVM) has succeeded in penetrating into the foundations of today’s medicine. A good place to start would be to monitor the prevalence of these modalities -not just across the realm of general practice where it thrives for the moment- but in some critical and pivotal place where CAVM could directly influence the concept of medicine itself.

What could be more crucial a place than the very halls of academia- where young professional minds begin their journey as physicians and veterinarians? In fact, Orac and Dr RW have long warned of this creeping infiltration of CAM into the halls of medical academia and associated institutions. The growing list of human medical institutions that Orac has been compiling is a sobering account (the academic woo aggregator) that this might be- at some level- a real threat to evidence based medicine and not just a fringe issue. Putting together this list is important as it begins to establish non-science and pseudo-science based medical modalities as something real in this important setting and therefore a topic well worth discussing.

It is in the fine tradition of copying a great idea that I will attempt to create a list of those veterinary institutions that may have some type of pseudo-scientific modality infiltrating their “sacred” halls.

It seems the job at hand might be easier as there are far fewer veterinary schools (27) in the US than medical schools. So, in the interest of shedding light on the level of CAVM involvement at US veterinary universities along with some modicum of morbid curiosity here is the pseudo-science in academia “veterinary academic woo aggregator” (This is only a cursory and partial list focusing mostly on teaching hospitals, somewhat on continuing education seminars- which may reflect university support, and to a smaller extent student clubs).

1) Colorado State University College of Veterinary Medicine

2) Iowa State University College of Veterinary Medicine

3) North Carolina State College of Veterinary Medicine

4) The Ohio State University College of Veterinary Medicine (externships)

5) Oregon State University College of Veterinary Medicine (continuing education)

6) Tufts Cummings school of Veterinary Medicine

7) UC Davis College of Veterinary Medicine Student Programs

(The holistic veterinary medicine club)

8) University of Florida Veterinary Medical Center

9) University of Minnesota Veterinary Medical Center

10) University of Pennsylvania School of Veterinary Medicine

11) The University of Tennessee College of Veterinary Medicine

12) Veterinary Medical teaching Hospital University of Wisconsin-Madison

13) Virginia-Maryland Regional College of Veterinary Medicine (elective complement med)

14) Washington State University College of Veterinary Medicine (Student Chapter)

College of Veterinary Medicine Student Chapter of the American Holistic Veterinary Medical Association

15) Cornell University College of Veterinary Medicine

This list -even if you take out the two student chapter associations- represents 48% of the veterinary universities in the US. Granted, at this early point, the veterinary academic woo aggregator only notes the existence of CAVM in academia- not the level or intensity.

Over all, it seems that infiltration of CAVM is not uncommon in academic veterinary hospitals, though it is often relegated to less obvious pain management or "support" areas- Colorado State University being one of the exceptions. However, the trend seems to be for “integrating” CAVM more into the fold. Whatever the case may be, the fact these unsubstantiated modalities exist in some form so insidiously in academia should be cause for increasing concern if not down right alarm.

CAVM and vet schools- the darkening (Part 2)

Sunday, January 27, 2008

Human evolution, fire, and food

From meat eating to cooking - the key to our minds?

What made us human? This age old question has been one of the foundational underlying motives –a holy grail- for generations of anthropologists through the ages. As the accumulating body of knowledge regarding our origins continues to grow and coalesce, a dim image of our evolutionary past is finally beginning to take on a recognizable shape.

One of the more interesting details among the blank pages of this incredible although incomplete body of knowledge is- what could have triggered the progression of an ancient hominid ancestor and prod it to follow a path that eventually led to “us”.

Indeed, this conundrum preoccupies more than just a few professional anthropologists in a grand quest for understanding. It has become apparent that an innumerable quantity of events- some major, others almost inconsequential- have contributed to the type of hominid we are today. It is highly likely this unique history will not repeat itself ever again in exactly same way even if a similar story unfolded somewhere else on another planet- or here in another time.

Peering far into the distant and foggy details of our past Richard Wrangham; professor of Biology and Anthropology at Harvard University, has pondered these fascinating issues searching for plausible key events that may have stoked the fire of evolution towards our state of being today. The improving anthropological data base and keen insight has allowed Wrangham to perhaps come upon what may be one of the very keys to our relatively short lived existence.

The rapid development of our brain size seems to be intimately intertwined with different developments in our history that created an interdependent chain of events that basically fed off of each other. The move to bipedalism may have allowed various advantages for certain primate ancestors to adaptively radiate into new and changing environments. A few of these lineages may have survived and developed certain social and technological advances allowing further opportunity to expand. Alas, of these it seems almost none survived the ruthless demands of nature except perhaps a few primate-like lineages.

At a time somewhere around 2.6 million years ago among these hominid creatures –pre-human bipeds- there appeared a fossil species names Homo habilis that according to Wrangham “…tell of incipient humanity, but…their chimpanzee-sized bodies, long arms, big guts and jutting faces made them ape-like.” It seems the anthropolic record shows that it is this hominid lineage that stumbled upon a new and heretofore unprecedented source of food (at least consistently)-meat eating. Though a huge milestone towards the eventual emergence of our own kind, it may not have been key we thought it was to the type of brain expansion that followed.

A million years would follow before the human like Homo erectus appears on the scene. These hominids differ from habilis and closely resembled our own species. Wranghem notes “Their brains were bigger than those of habilis, and they walked and ran as fluently as we do…To judge from the reduced flaring of their rib cage they had lost the capacious guts that allow great apes and habilis to eat large volumes of plant food. Equally strange for a “helpless and defenseless” species they had also lost their climbing ability, forcing them to sleep on the ground- a surprising commitment in a continent full of big cats, sabretooths, hyenas, rhinos, and elephants.”

Wringham realized these peculiar findings could be a telltale sign of one of those key milestones that accelerated evolutionary brain expansion in hominids. It had been believed that meat eating was one of these fulcrum moments- but as we noted- the improving fossil record has pre-human hominids such as H. habilis meat eating well before truly human like qualities began to emerge as in H. erectus. While meat eating was a crucial development, what other condition could have occurred during this period that finally put one habilis group firmly on the road to humanity?

Here Wringham posits a truly fascinating possibility, one that rings true and threads nicely into the tapestry of how we came to be from them. He suggests that it was the control of fire and the ingestion of cooked food that changed everything. In spite of the fact fire use becomes spottier the farther back in the historical record you go, Wringham maintains that this clutch tool could have triggered the cascade. In fact, it is interesting to note that evidence for the use of fire –spotty though it may be- goes as far back as 1.6 millions years to about the time H.erectus appeared.

Based on this “epiphany” Wringham came to some realizations that indeed have solid merit. He claims that “humans are biologically adapted to eating cooked diets, and the signs of this adaptation start with Homo erectus. Cooked food is the signature feature of the human diet. It not only makes our food safe and easy to eat, but it also grants us large amounts of energy compared to a raw diet obviating the need to ingest big meals. Cooking softens food too, thereby making eating so speedy that as eaters of cooked food, we are granted many extra hours of free time every day.” This situation may have been a key catalyst for the subsequent exponential expansion of technological and socio-cultural development.

This fascinating theory offers a window into a critical period of human evolution that opened the doors to the emergence of H. sapiens. As we expand our understanding of human origins, it is becoming abundantly clear just how mundane we truly are- that we are just another animal driven completely by the rule of evolution and the whims of happenstance. Our “unique and special” mental capacity is really just another reflection -among many- of nature’s possibilities

Friday, January 25, 2008

Veterinary chiropractic, elusive “Vertebral subluxations”…

…and other sundry details…or a hundred years of talk and still no answers

The skills necessary to practice medicine takes years of persistent and focused effort. During the course of becoming a truly prepared doctor, aspiring students must retain an enormous mass of learned information, gather it into a working knowledge base, and successfully -with this base- bring to life a flexible and effective problem solving system. That is, aspiring doctors need to learn how to tease out meaning and develop direction in an ever changing environment of real life and death- full of unknown variables. This aptly describes the fluid state of medical practice.

One extremely important condition that has allowed this enterprise to work effectively (for the last one hundred years or so) is the fact that medicine has tempered and restrained its ego enough to keep itself within the framework of tested reality- a firm data base if you will. This medical data base has become a growing maze of interlocking bits of information, each adding to a sum total that coalesces into a robust, dependable, and usable system of knowledge.

Alas, this one critical and non-negotiable condition -key for attaining any real chance at legitimacy- is missing in chiropractic theory and practice. Since its inception, with very few exceptions, chiropractic medicine has labored under the rubric of the “subluxation” a concept that, to this day, remains elusive and mysterious.

The practice of chiropractic has been described as a diagnostic illusion; a discipline that has been constructed on very precarious foundations. Though this modality claims to treat the cause of a patients’ problem- it doesn’t at all. The core diagnosis in chiropractic practice; usually some form of the “subluxation complex”, is either non-existent or a result of a real organic disease. For example, many of the conditions interpreted as or resulting from subluxations -some of which can be localized- are actually a plethora of other maladies including bony asymmetry, conformational issues, muscular adhesions, ligamentous contracture, weak musculature, and a myriad of generalized maladies.

In veterinary medicine- and human medicine for that matter- the definition of a “vertebral subluxation” or “vertebral subluxation complex” has gone through a number of revisions over the years in what has been a futile attempt to pin this concept down and connect it to something tangible. The “subluxation”, "vertebral subluxation complex", or whatever you would like to call it is a term that describes a constellation of signs and symptoms that, chiropractors claim, result from a misaligned or dysfunctional spinal segment (and different from the rare and verifiable medical luxation describe in evidence based medicine). The Association of Chiropractic Colleges defines it as a “complex of functional and/or structural and/or pathological articular changes that compromise neural integrity and may influence organ system function and general health.” This seems to cover just about anything!

Alan Schoen DVM, a prominent promoter of Complementary and Alternative Veterinary Medicine (CAVM), defined veterinary chiropractic therapies at the 2001 World Small Animal Veterinary Association Congress “…as the art and science of diagnosis and correction of dysrelationships between the nervous system and the spinal column through manual spinal manipulation.”

He goes on to describe that the concept of a subluxation “is completely different to a veterinarian and a chiropractor, leading to numerous misunderstandings and debates. One needs to look at current definitions in order to better understand chiropractic concepts. These definitions and concepts are evolving as well… From a chiropractic perspective, a vertebral subluxation complex is defined as a disrelationship between a vertebral segment in association with contiguous vertebrae, resulting in disturbance of normal biomechanical and neurologic function.” These rather vague descriptors of the core premise for chiropractic are typical of the efforts to give this modality an air of credibility. However, they add nothing to the discussion of what a “subluxation” is, how it can be reliably diagnosed, and how it relates to the previously mentioned sum total of dependable medical knowledge.

Unfortunately, purveyors of chiropractic don’t stop with first trying to define and confirm the existence of this entity- they go on to create a huge body of detail that includes imaginative pathophysiological causal mechanisms and a whole litany of chiropractic therapies that comprises the so called “chiropractic paradigm.” The problem is if you can not independently identify the object in question, confirm and establish any effects it may produce, or consistently link it to solid evidence you are basically chasing ghosts.

Supporters of the “veterebral subluxation complex” claim that it can negatively impact general health interfering with the proper function and healing of the body because the nervous system controls a broad array of organ systems- though we are only given unproven theories as to how (fig.1).


(Fig 1) Example of unsubstantiated etiologic theories for how a “subluxation could cause disease: V. Strang, D.C., “Essential Principles of Chiropractic”1.

  • Nerve compression hypothesis: suggests that when the vertebrae are out of alignment, the nerve roots and/or spinal cord can become pinched or irritated. While the most commonly referenced hypothesis, and easiest for a patient to understand, it may be the least likely to occur.
  • Proprioceptive insult hypothesis: focuses on articular alterations causing hyperactivity of the sensory nerve fibers.
  • Somatosympathetic reflex hypothesis: all the visceral organ functions can be reflexly affected by cutaneous or muscular stimulation.
  • Somatosomatic reflex hypothesis: afferent impulses from one part of the body can result in reflex activity in other parts of the body.
  • Viscerosomatic reflex hypothesis: visceral afferent fibers cause reflex somatic problems.
  • Somatopsychic hypothesis: the effects of a subluxation on the ascending paths of the reticular activating system.
  • Neurodystrophic hypothesis: focuses on lowered tissue resistance that results from abnormal innervation.
  • Dentate ligament-cord distortion hypothesis: upper cervical misalignments can cause the dentate ligaments to put a stress on the spinal cord.
  • Psychogenic hypothesis: emotions, such as stress, causing contraction in skeletal muscles.


Dr Schoen states that “The pathophysiology of subluxation complexes includes compression of spinal nerve roots or the spinal cord, vertebrobasilar arterial insufficiency, somatovisceral dysfunction, and decreased mobility.” This is similar to many of the anatomical and functional theories described by other practitioners- sound nice, but where is the proof?

These “dysfunctions” are treated by a plethora of therapies some of which seem reasonable (i.e.; rest, massage, stretching excersizes) but most -in their majority- appear to be based on dubious alternative recommendations and techniques (i.e.; acupuncture, muscle testing, unusual hair and blood analysis testing, laser therapy, magnetic therapy, nutritional supplement therapy). Still, by far, the core treatment modality used by chiropractors in animals and humans remains the familiar “adjustment or manipulation”.

Schoen defines these two modalities successively as follows“<an adjustment is > a ‘short-lever, high-velocity, quick thrust’ with specific force applied in a specific direction to a specific vertebra and designed to deliver maximal force with minimal tissue damage. Manipulation distributes the force to multiple segments via “long-lever, slow velocity, non-thrust” techniques. These are all based on Wolf’s Law that ‘structure follows function.’ In other words, that functional problems precede actual structural defects.”

The mention of Wolfs law is a good example of how tangentially related concepts are cherry picked and mentioned in the same breath with implausible notions- such as the above described manipulations.2 Wolfs law describes a physiological response over time of bone to a variety of loading situations- not including periodic chiropractic adjustments or manipulations.Stating that functional problems precede structural defects is like saying all diseases are caused by nutritonal deficiencies. Broad sweeping statements are often incomplete or false and may reflect a profound misreading of what scientific observations actually reveal.

“Vertebral subluxations” are thought to involve one or more spinal units (two vertebral articar faces and all the corresponding tissues). The fuzzy “vertebral subluxation complex”, though more abstract is still approached primarily through manipulations. Chiropractic treatment is therefore oriented at targeting the affected part or parts of the spine in order to reduce a “subluxation” or correct physiological disruption.

Dr Schoen goes on to imply that by adjusting an animal and correcting the subluxation the affected neurological pathways are no longer hindered or compressed and the flow of impulses improves thereby resulting in a healthier status. This is reminiscent of the original vitalistic “energy” related beliefs invented by DD Palmer; the originator of chiropractic therapy.

In medicine, it is important to localize and identify the systems involved in disease and to monitor the evolution and effects of treatment- all important criteria for science based medical treatments. The problem is veterinary chiropractic is not dependant on the findings of modern medical problem solving techniques -though it will often “piggy back” and be “integrated” with those findings- it can also just as easily be implemented independently of any established science. This is because chiropractic medicine is not threaded and tied into the robust system of modern medicine- not a good thing.

In this vein, Dr Schoen correctly adds “Veterinary chiropractic research is limited.” and notes that “Most recent research has been conducted by Dr. Kevin Hausler at Cornell Veterinary School, where he documented mobility of the equine spine and demonstrated equine spinal movement following a chiropractic adjustment.” This may refer to a small study published later in 2007 regarding the relationship between spinal kinematics (movement) and specific spinal manipulations after attempting to surgically induce back pain in a group of ten horses. This study found a very modest improvement in spinal “flexibility” in the thoracolumbar region when treated horses were exercised on a treadmill as compared to a control group.

Though intriguing, this observation does not constitute any type of explanation or validation for the “subluxation complex” and the results may or may not even be real.3 In any event, the data is indeed minimal with respect to a establishing any scientific underpinning for veterinary chiropractic theory. It is worth noting, that the present scarcity in humans of validated research regarding the “subluxation complex” makes animal research even less promising.

An example of how some chiropractors have responded to this criticism includes an article by Ted Koran DC in which he states “Subluxations, genes, gravity, the ego and life are all heuristic devices, "useful fictions" that are used to explain phenomenon that are far larger than our understanding. We use them as long as they work for us and discard or limit their application when they become unwieldy or unable to account for new observations... Critics of chiropractic have incorrectly assumed that chiropractic is based on the theory or principle that vertebral subluxations cause "pinched" nerves that cause disease. They have it backwards. Chiropractic is based on the success of the spinal adjustment. The theory attempting to explain the success of the adjustment (nerve impingement, disease, subluxations) followed its clinical discovery.” 4 The problem with this position is that the subluxation has no where near the foundation and usefulness this doctor thinks. Associating “success” to spinal adjustments is an unsubstantiated assumption- a fallacy- making the rest of his argument rather tenuous and meaningless.

To date, the “vertebral subluxation complex” has no documented natural history (you can not feel it, see it, nor follow its evolution clearly) making it impossible to objectively grade and classify5 and is not a verifiable pathological entity in animals (nor humans). So, if you can’t describe it and you can’t truly localize it- how can you treat it?

Dr Schoen notes that “The future of chiropractic is to include it in a professional manner as an integral part of veterinary medicine.” Sadly, this is another example of a therapeutic modality making an unearned and premature rush towards the world of legitimacy typical of Complementary and Alternative therapies.

The concept of chiropractic vertebral subluxation remains a uniquely chiropractic model not associated or supported by the scientific consensus in human and veterinary medicine. Any benefits from “adjustments” or other chiropractic therapies are likely to be coincidental and actually a result of -among other things- complex placebo effects and the waxing/waning course of chronic disease (natural history of disease).

An article written by supporters of the “subluxation” as a valid- albeit unproven- theory lamented the “dogmatic” approach the chiropractic establishment holds with regards to this concept. Though we may disagree on whether “subluxation” is a valid theory, the authors do candidly and correctly note that “…What must be avoided... is the unreasonable extrapolation of current knowledge into speculation and presentation of theory as fact. Given the current deficiency of empirical data, the only sound scientific-epistemological position that we can conceive of is to acknowledge our ignorance: we don't know if subluxation is clinically meaningful or not. We suggest that this is a requisite first step toward greater wisdom concerning subluxation." 6 On that at least, we can agree.

That chiropractic theory is built on such a tenuous and fragile premise makes it an interesting- yet fictional- belief based enterprise in human ingenuity. Ultimately, veterinary (and human) chiropractic is like the story of the naked king surrounded by worshiping servants. No matter how beautiful their description of his “dress” is- the fact remains that the emperor still has no clothes.


1) Strang, V (1984) Essential Principles of Chiropractic Davenport : Palmer College of Chiropractic, OCLC: 12102972

2) Wolffs' law states “that bone in a healthy person or animal will adapt to the loads it is placed under. If loading on a particular bone increases, the bone will remodel itself over time to become stronger to resist that sort of loading. The external cortical portion of the bone becomes thicker as a result. The converse is true as well: if the loading on a bone decreases, the bone will become weaker due to turnover as it is less metabolically costly to maintain and there is no stimulus for continued remodeling that is required to maintain bone mass.”

3) As with any study, this one needs to be critically analyzed and possibly pooled with other research in equine spinal kinematics. Any significant findings, if found, would then need to be looked into. If there are benefits they should be noted. However, assuming there was some type of positive effect it is more likely due to more readily explainable phenomena such as relaxation or counter irritation than to actions related to the theory behind the “manipulation”. Additionally, other studies researching normal equine kinematics can shed light on the validity of this particular study. On top of that, we have to deal with how this may or may not relate to the rest of the animal kingdom!

4) Chiropractic's Elusive Subluxation - Does the Vertebral Subluxation Exist? - Tedd Koren.

5) For example there is no way to grade different levels of subluxation based on severity, cause, age of patient, anatomical region where it is found, whether it affects populations differently, or if there is any genetic involvement.

6) Keating J, Charlton K, Grod J, Perle S, Sikorski D, Winterstein J (2005) Subluxation: dogma or science? Chiropr Osteopat. 2005; 13: 17. available online

Other ref:

Chirotalk: The skeptical chiropractic discussion forum

Ramey, D. Veterinary chiropractic.