Veterinary chiropractic revisited

In one of my last posts, I was rather dismissive of veterinary chiropractic.

Was I too harsh?

I did ask readers who disagree with my judgment to send me their evidence.

Sadly, none arrived!

Therefore, I did several further literature searches and found a recent review of the topic. It included 14 studies; 13 were equine and one was a canine study. Seven of these were cohort studies and seven were randomized controlled clinical trials. . Study quality was low (n = 4), moderate (n = 7), and high (n = 3) and included a wide array of outcome parameters with varying levels of efficacy and duration of therapeutic effects, which prevented further meta-analysis. The authors concluded that it was difficult to draw firm conclusions despite all studies reporting positive effects. Optimal technique indications and dosages need to be determined to improve the standardization of these treatment options.

This, I think, can hardly be called good evidence. But I also found this more recent paper:

Chiropractic care is a common treatment modality used in equine practice to manage back pain and stiffness but has limited evidence for treating lameness. The objective of this blinded, controlled clinical trial was to evaluate the effect of chiropractic treatment on chronic lameness and concurrent axial skeleton pain and dysfunction. Two groups of horses with multiple limb lameness (polo) or isolated hind limb lameness (Quarter Horses) were enrolled. Outcome measures included subjective and objective measures of lameness, spinal pain and stiffness, epaxial muscle hypertonicity, and mechanical nociceptive thresholds collected on days 0, 14, and 28. Chiropractic treatment was applied on days 0, 7, 14, and 21. No treatment was applied to control horses. Data was analyzed by a mixed model fit separately for each response variable (p < 0.05) and was examined within each group of horses individually. Significant treatment effects were noted in subjective measures of hind limb and whole-body lameness scores and vertebral stiffness. Limited or inconsistent therapeutic effects were noted in objective lameness scores and other measures of axial skeleton pain and dysfunction. The lack of pathoanatomical diagnoses, multilimb lameness, and lack of validated outcome measures likely had negative impacts on the results.

Great! So, we finally have an RCT of chiropractic for horses. Unfortunately, the study is less than convincing:

• It included just 20 polo horses plus 18 horses active in ridden or competitive work all suffering from lameness.
• The authors state that ‘horses were numerically randomized to treatment and control groups’; yet I am not sure what this means.
• Treatment consisted of high-velocity, low-amplitude, manually applied thrusts to sites of perceived pain or stiffness with the axial and appendicular articulations. Treatment was applied on days 0, 7, 14, and 21 by a single examiner. The control group received no treatment and was restrained quietly for 15 min to simulate the time required for chiropractic treatment. In other words, no placebo controls were used.
• The validity of the many outcome measures is unknown.
• The statistical analyses seem odd to me.
• No correction for multiple statistical tests was done.
• Most of the outcomes show no significant effect.
• Overall, there were some small positive treatment effects based on subjective assessment of lameness, but no measurable treatment effects on objective measures of limb lameness.
• The polo horses began their competition season at the beginning of the study which would have confounded the outcomes.

What does all this tell us about veterinary chiropractic?

Not a lot.

All we can safely say, I think, is that veterinary chiropractic is not evidence-based and that claims to the contrary are certainly ill-informed and most probably of a promotional nature.