I used to schedule regular chiropractic sessions for my horse because I was convinced this was just another aspect of good horse husbandry. But after observing each of my $175 sessions, I began to have serious doubts. For instance, my veterinary chiropractor, who was also a human chiropractor, explained that with the pressure of two fingers, she could move my horse’s ribs back “into alignment.” Having some knowledge of physical anatomy, I wondered how it was possible to do this, and what would prevent the ribs (or any other aspect of the equine musculoskeletal system) from becoming unaligned 5 minutes after she left? After all, if all it took were two fingers to pop a rib back in place, wouldn’t I be having some counterbalancing effect just by putting a saddle on my horse’s back? Or what if she just rolled in the pasture? Would that undo the $175 treatment I had just paid for?
My own opinion is that chiropractors aren’t necessarily producing lasting results because they may not be treating an underlying muscle problem, which I believe is the root cause of most discomfort in horses. Equine Myofascial Release will help move the bone by addressing the actual problem which is the muscle, tendon, ligament. The bone is a slave to the muscle – it can only move if the muscle tells it to move. And, it can only be where the muscle allows it to be. If you can even move the bone, but the horse’s muscle is still tight, the muscle will pull the bone back “out of place.” Why not just go to the source of the problem – the soft tissue or skeletal muscles themselves – with either massage or EMR?
I wondered what I was missing, since other clients in the same barn claimed their horses moved better instantly after receiving their treatments. Placebo is “the beneficial effect that arises from a patient’s expectations from a treatment, rather than from the treatment itself.” Does the placebo effect exist in animals? Until recently, the presumed answer was a resounding no, because animals were thought to lack the cognitive capacity to understand the intent of medical care or the power of suggestion, or to have hope of recovery.
A veterinary journal article entitled “The placebo effect in animals,” makes a case for the existence of the placebo effect in dogs, among other species. The article suggests that the placebo effect in veterinary medicine can enhance the efficacy of medical treatment, and findings make a “strong scientific argument for encouraging in-hospital visitation by owners when animals are hospitalized.”
I don’t know whether animal chiropractic helps pets or not. But unlike allopathic (conventional) medical treatments, I can’t see the results of long-term therapy. I prefer to employ massage for horses, since I can see my horse lean into the practitioner, relax her ears, and close her eyes, which is strongly suggestive that the treatment relaxes her and makes her feel good. The massage therapist uses firm hands on large muscle groups. With the chiro treatments, my horse pinned her ears and generally appeared annoyed or perhaps found the treatments ticklish. When my regular chiropractor retired, I still continued on for a while, and was fortunate enough to be able to use the services of an FEI treating veterinarian who was also an equine chiropractor. My confidence in equine chiropractic was finally shattered when he told me that he didn’t have any suggestions for my horse’s lameness other than conventional treatments, which weren’t a guarantee either. Because…….there are no magic cures.
Written by: Brennen McKenzie, MA, VMD, a 2001 graduate of the University of Pennsylvania School of Veterinary Medicine. He works as a small animal veterinarian in private practice in California. He has a special interest in promoting science-based veterinary medicine and is currently President-Elect of the Evidence-Based Veterinary Medical Association. He has published articles on evidence-based medicine in veterinary science journals, and he also writes about both science-based and “alternative” veterinary medicine as the SkeptVet.
Prior to becoming a veterinarian, Dr. McKenzie completed a Master’s Degree in animal behaviour, studying captive chimpanzees and working as a specialist in environmental enrichment for captive primates.
People are sometimes surprised to learn that all the heavy hitters of alternative medicine, such as acupuncture, chiropractic, homeopathy, etc., are inflicted on animals as well as humans. I’ve written about veterinary homeopathy, and the associated manufactroversy, in a previous post, and today I thought I’d take a look at veterinary chiropractic.
The Players
In most states, chiropractic is defined in terms of treatment of humans and chiropractors are thereby licensed only to treat humans. However, there are a variety of ways around this for people who want to subject their animals to this therapy. Some chiropractors will simply treat animals and ignore the fact that it isn’t technically legal for them to do so. And some veterinarians will take one of the many training courses available in animal chiropractic and then employ it as part of their practice of veterinary medicine. A previous SBM article has discussed the lack of consistency or legitimate scientific content in most of these courses.
State veterinary practice acts will also sometimes create legal space for animal chiropractic, often under another name, which avoids the jurisdictional problem of calling it chiropractic when that term is usually legally defined specifically with reference to humans. In California, for example, the practice of “musculoskeletal manipulation” on animals must meet certain requirements specific in the state veterinary practice act:
A veterinarian must examine the animal, determine that musculoskeletal manipulation (MSM) is appropriate and safe, and take official responsibility for supervising the treatment. Then the owner is supposed to sign a form: “The veterinarian shall obtain as part of the patient’s permanent record, a signed acknowledgment from the owner of the patient or his or her authorized representative that MSM is considered to be an alternative (nonstandard) veterinary therapy.”Then a licensed chiropractor can examine the pet, determine that MSM is appropriate, and then consult with the supervising vet before performing treatment.
I know of many chiropractors treating animals in the state, with and without veterinary supervision. I have never seen anyone follow these rules.
The perceived legitimacy of veterinary chiropractic is bolstered by the activities of professional veterinary chiropractic organizations, such as the American Veterinary Chiropractic Association 
(AVCA). This group offers a certification program which allows either chiropractors or veterinarians to claim to be board-certified in animal chiropractic, despite the technicality that the American Board of Veterinary Specialties, which credentials specialty boards, does not recognize this certification and thus it is essentially a fake board certification.
The International Veterinary Chiropractic Association (IVCA), based in Europe, is largely indistinguishable from the AVCA in terms of the content and general approach to promoting animal chiropractic and certifying chiropractors, including the lack of recognition of their specialty certification by the European Board of Veterinary Specialisation (EBVS).
These groups are not to be confused with the International Association of Veterinary Chiropractitioners (IAVC), a group of veterinarians, chiropractors, and apparently any other kind of “health care provider” who cares to join, who fix subluxations with methods difficult to distinguish from chiropractic but who claim to be practicing an entirely original form of therapy called Veterinary Orthopedic Manipulation (VOM) and who prefer to be referred to by the proprietary term “chiropractitioner.” They do share, however, the lack of any formal recognition as a legitimate specialty that characterizes the work of the AVCA and the IVCA.
And then, of course, there are all the individual chiropractors and veterinarians practicing some form of manual therapy based on chiropractic, often with their own idiosyncratic theories and techniques. For example, Dr. Hall recently drew my attention to a book called “Like Chiropractic for Elephants” by Norman “Rod” Block D.C. Dr. Block claims to have “an uncanny touch sensory perception that allows him to connect with the person or animal he comes in contact with…It is then that the animal senses his intention of wanting to help and releases inhibitions that allow discovery of where the root cause of the pain, stress or pressure may exist…The doctor uses his uncanny ability to tune into the root cause of animal states of disease without the use of drugs or surgery.”
I confess I have not been able to stomach paying to read Dr. Block’s book, but thanks to his press release and a few reviews, I have at least a small sense of what it offers. Apparently Dr. Block supplements his understanding of the vertebral subluxation and his “uncanny” sensory abilities with the practice of “Quantum Shamanetics.” In this method, “The quantum shamanist learns to trust and be guided by universal wisdom that exists beyond our genetic blueprint. By being part to, and observing, movement, one becomes more sensitive to subtle changes in energy. By following these dynamic changes, the shamanist develops a more expansive relationship with the flow of life and health.”
Sadly, this is not a unique case of a chiropractor leaving the at least marginally plausible terrain of treating musculoskeletal disease in animals and venturing further afield. Last year, I had the opportunity to evaluate the recommendations of Dr. Steven Eisen, a chiropractor who calls himself a “Holistic Dog Cancer Expert” and has a book and series of web videos explaining how to thwart the mischief of incompetent veterinarians and treat canine cancer with his dietary advice and a dedicated avoidance of vaccines and parasite control products. And perhaps not surprisingly, Dr. Eisen did not exhibit the scientific spirit of respect for open inquiry and debate when challenged for his claims. Instead, he threatened to sue me.
What Is Animal Chiropractic?
For the most part, the principles and practices of animal chiropractic are extrapolated and adapted from those applied to humans, despite the obvious biomechanical and anatomic differences between bipedal hominids and quadrupedal veterinary patients. As in human chiropractic, the core concept behind chiropractic for animals is the subluxation, or the vertebral subluxation complex (VSC). The AVCA criteria for certification includes familiarity with, “the anatomical, biomechanical and physiological consequences of the Vertebral Subluxation Complex,” and the organization suggests that in addition to pain and musculoskeletal disorders, treatment of the VSC can be beneficial for “bowel, bladder, and internal medicine disorders…glands and body functions.”
Veterinary journal articles about chiropractic often emphasize that the subluxation “is at the core of chiropractic theory, and it’s detection and correction are central to chiropractic practice.”(1) 
They then include lengthy, very impressive and sciency descriptions of how subluxations arise, cause disease, and can be treated. These are usually marred only by the small problem that no one has actually been able to show a subluxation exists in any species despite over a century of trying.(2)
Chiropractors working on humans cannot reliably agree on the location of a supposed subluxation despite extensive and involved theoretical and practical training supposedly intended to help them do so.(3-4) You can’t see it on x-rays, it doesn’t pinch nerves, and as the evidence for subluxations as physical abnormalities has failed to materialize, true believers in chiropractic have gone through amazing intellectual contortions to redefine it in ways that can make it sound real while still being undetectable. A dragon in the garage if there ever was one.
What’s the Evidence?
There is at least some reasonable evidence that spinal manipulations such as practiced by chiropractors may benefit humans with back pain, though Cochrane reviews of spinal manipulation and general chiropractic therapy for even this indication find small effects and research with a high risk of bias. There is no good reason to believe chiropractic is useful for any other complaint in humans.
Reviewing the literature on the effects of veterinary chiropractic care is quite easy since there is almost none. A search of the PubMed and VetMed Resource databases identified no controlled clinical trials of chiropractic therapy in any veterinary species.
Apart from a few case reports, there are several studies evaluating the putative effect of spinal manipulations on sensitivity to painful stimulus and on spine and limb movement in horses.(5-7) These papers suffer from significant limitations and risk of bias. They generally show a lack of adequate randomization and blinding, objective outcome measures and control groups. They frequently measure numerous variables of questionable clinical significance and then ignore the majority that show no change while identifying the few that do show statistically significant differences as somehow indicative of a meaningful treatment effect. While they represent a reasonable attempt to identify criteria for evaluating the effects of spinal manipulation on horses, they do not constitute evidence of efficacy for chiropractic therapy for any disease.
Of course, there is the usual mountain of testimonials and anecdotes which suggest miraculous curative results with chiropractic therapy in animals. These are both unreliable, for all the usual reasons, and unfortunately the most compelling kind of evidence for animal owners
What’s the Harm?
The risks of chiropractic care in humans fall into the usual categories for harm from alternative therapies; direct harm from the treatment and indirect harm associated with irrational belief systems and avoidance of truly effective care. Of the adverse effects documented in humans, the most significant is that of strokes associated with cervical manipulation.(8) There is no research evaluating the direct risks of veterinary chiropractic, so we can only speculate on the safety of spinal manipulation for animal patients.
The indirect risks of chiropractic therapy come from being exposed to irrational fear of science-based medicine and the use of other unproven or clearly ineffective alternative treatments. Chiropractors treating humans, for example, are often inclined to recommend against vaccination, and it is not uncommon for them to employ therapies far less plausible than chiropractic, such as colon cleansing, homeopathy, and many others.
Chiropractors practicing on animals have also been known to stir up irrational fear of vaccination, claim toxins in pet food are common causes of cancer, and otherwise express disdain for science-based veterinary medicine. And a look at the sponsors for the ACVA annual conference illustrates the frequently close relationship between animal chiropractors and practitioners of other alternative therapies such as Traditional Chinese Veterinary Medicine, Standard Process Supplements, Reiki and homeopathy, and others. Such synergy between chiropractic and other alternative therapies has the potential to harm veterinary patients even if direct spinal manipulation does not.
Since anecdotes are so commonly employed in defense of veterinary chiropractic, I feel justified in sharing one illustrating its risks. I was once asked to examine a rabbit that had come to my hospital to be treated by a chiropractor, at the advice of another veterinarian. The rabbit had been anesthetized for treatment of dental disease earlier in the day and upon waking was paralyzed in its hind legs. Even a cursory familiarity with rabbit medicine would immediately lead one to consider a fracture or dislocation of a lumbar vertebrae since these can happen when rabbits kick their powerful hind legs uncontrollably, and rabbits are susceptible to disorientation and panic when emerging from anesthesia.
The chiropractor had already examined the rabbit and concluded it had a subluxation in its cervical spine. He recommended giving a chiropractic adjustment to the neck and sending the pet home, with additional adjustments likely necessary in the following days or weeks. When I asked how he reconciled his diagnosis with the symptoms, which fit the classic pattern associated with a spinal cord injury in the lower back, the chiropractor informed me that he was familiar with “allopathic” neurology textbooks but had chosen to ignore them because they were not consistent with his daily experience in practice.
The client permitted me to take an x-ray which confirmed a traumatic lumbar vertebral fracture and severe spinal cord trauma. The patient was humanely euthanized in light of the severe 
symptoms and poor prognosis. Though this was sad, I consider it a better outcome for the animal than having its neck twisted and being sent home paralyzed and with a fractured spine but without any pain control, as the chiropractor had recommended. Granted, such a story cannot prove anything about the safety or efficacy of animal chiropractic therapy, but it is at least illustrative of some of the risks of substituting a pseudoscientific belief system for science-based medicine.
Bottom Line
Though there is no reliable data, the popularity of chiropractic for treatment of humans appears to translate, to at least some extent, to the treatment of animals. The fundamental theories and practices of animal chiropractic are copied or extrapolated from those employed in treating humans, however there is virtually no reliable scientific evidence to show any benefit from veterinary chiropractic treatment. There is also no controlled evidence identifying the risks of chiropractic therapy of animals, so we can only speculate about the safety of this intervention. It is clear, however, that chiropractic therapy for animals is often associated with opposition to conventional medical care and with other unproven or clearly ineffective alternative therapies, and this presents some risks to patients seeking care from so-called animal chiropractors.
References
- Maler, MM. Overview of veterinary chiropractic and its use in pediatric exotic patients. Vet Clin Exot Anim. 2012;15:299-310
- Miritz TA. Morgan L. Wyatt LH. Greene L. An epidemiological examination of the subluxation construct using Hill’s criteria of causation. Chiropr Osteopat 2009;2:17-13.
- French SD, Green S, Forbes A. Reliability of chiropractic methods commonly used to detect manipulable lesions in patients with chronic low-back pain. J Manipulative Physiol Ther. 2000 May;23(4):231-8.
- Hestbaek L, Leboeuf-Yde C. Are chiropractic tests for the lumbo-pelvic spine reliable and valid? A systematic critical literature review. J Manipulative Physiol Ther. 2000 May;23(4):258-75.
- Haussler, KK. Martin, CE. Hill, AE. Efficacy of spinal manipulation and mobilisation on trunk flexibility and stiffness in horses: a randomised clinical trial. Equine Veterinary Journal. 2010; 48 (Supp. 38):695-702.
- Gomez Alvarez, CB. L’Ami, JJ. Moffatt, D. van Weeren, PR. Effect of chiropractic manipulations on the kinematics of back and limbs in horses with clinically diagnosed back problems. Equine Veterinary Journal. 2008;40(2):153-159.
- Sullivan, KA. Hill, AE. Haussler, KK. The effect of chiropractic, massage and phenylbutazone on spinal mechanical nociceptive thresholds in horses without clinical signs. Equine Veterinary Journal. 2008;40(1):14-20.
- Ernst, E. Adverse effects of spinal manipulation: a systematic review. J R Soc Med July 2007 vol. 100 no. 7 330-338
© Heather Clemenceau
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