New Study Shows No Benefit from Acupuncture for Dogs with Arthritis

I have written extensively over the years about acupuncture, and my investigations have ranged from the laboratory animal and human literature to veterinary clinical studies, to completing a certification in medical acupuncture and treating patients in my clinic. Through all of this, I have found little to change my basic views of acupuncture, summarized in my latest article on the subject:

Most acupuncture treatment is still based on unscientific religious and philosophical principles. Despite extensive research over many decades, plausible scientific explanations for how traditional acupuncture might work have not been clearly validated. Clinical studies in humans have failed to find clear evidence of meaningful benefits for most conditions compared with sham interventions. 

There is little high-quality clinical research on veterinary acupuncture, and the widespread belief that it is an effective therapy is based mostly on anecdote and low-quality evidence. Better research evidence has been challenging to generate due both to the difficulty in creating an effective placebo comparator for acupuncture and to the impact of entrenched bias and unscientific beliefs among acupuncturists evaluating the practice.

Put more succinctly, the principles are either unscientific or unproven, it probably has little if any benefit, and it is relatively low-risk if applied sensibly and note used in place of science-based medicine. A recent clinical study in dogs with arthritis serves as additional support for these views.

Baker-Meuten A, Wendland T, Shamir SK, Hess AM, Duerr FM. Evaluation of acupuncture for the treatment of pain associated with naturally-occurring osteoarthritis in dogs: a prospective, randomized, placebo-controlled, blinded clinical trial. BMC Vet Res. 2020;16. doi:10.1186/S12917-020-02567-1

This was a nicely done study illustrating the use of some methods for objectively evaluating acupuncture in veterinary patients. Like most veterinary studies, it was small, with only 36 dogs (4 of which did not complete the study). The design was a crossover study, meaning all patients got both acupuncture and placebo treatment and were randomly assigned to get one or the other first with a washout period between treatments. This is a good way to minimize the errors that can be creep into the data if dogs with different characteristics get different treatments. For example, if the dogs in the placebo group had much worse arthritis than the dogs in the acupuncture group, it could easily look like the treatment was working even when it wasn’t.

There was also an effort at blinding, meaning the owners weren’t supposed to know when their dogs got placebo treatment and when they got acupuncture. This would help reduce the tendency of people who already believe in the effectiveness of acupuncture to see improvement due to caregiver placebo effects. Unfortunately, this blinding didn’t appear entirely successful. About 58% of owners correctly guessed when their dogs were getting acupuncture or placebo and only 19% guessed incorrectly (the rest said they couldn’t tell). While assessing the success of blinding is a good idea, a well-blinded study should have roughly equal numbers of people guessing real and placebo treatment. The veterinary staff and investigators were not blinded, which is unfortunate since this can not only bias the assessment of whether the treatment works but also subtly influence the perceptions of the owners, which may have been the case in this study.

The investigators used both subjective measures of effect, by both owners and veterinarians, and also objective measures, activity monitors and a force plate that measures the amount of weight a dog with arthritis can put on a painful limb. 

The treatment was a standardized acupuncture protocol based on a survey of veterinary acupuncturists, both from the Traditional Chinese Medicine school and also from the somewhat more scientific Medical Acupuncture trainingbackground. Some will still undoubtedly complain that this invalidates the results since theoretically acupuncturists treat every patient with a unique approach based on whatever set of theories they believe in and their own clinical experience. However, there was tremendous overlap among the vets surveyed in the approaches they used, and there is no evidence to support the claim that haphazard individualization of treatment works any better than standardized protocols. 

The treatment also involved electrical stimulation through the acupuncture needles. There is some debate about whether this is really “acupuncture” or simply a form of electrical nerve stimulation dressed up in folk medicine clothes. There is slightly better evidence for potential benefits to such electroacupuncture than for needling alone (“dry needling” as it is typically called) though the evidence is still not very robust.

The placebo was not a sham acupuncture treatment, as is often used. Instead, dogs were simply taken into the room where acupuncture would normally be done and spent an equivalent amount of time interacting with one of the veterinary staff. There are pros and cons to this approach. Defining sham acupuncture is tough because it is not clear that specific acupuncture points even exist or that it matters where you insert needles. In human studies, needling at a “fake” acupuncture point often has the same effect as needling at a “real.” This probably means the responses are mostly due to placebo effects and non-specific irritation from the needle insertion rather than some magical manipulation of energy or some special quality to the points traditionally used. However, if sham needling has the same effects as real acupuncture, then it doesn’t make a very good placebo control.

A non-treatment placebo avoids this problem, and it still controls for one of the most likely causes of placebo effects in animals, which is human contact. However, insofar as needling and electrical stimulation due have biological effects (whether clinically relevant or not), this is very different from just sitting in a room with a person, so arguably the placebo control isn’t very much like the treatment, and this opens the door for error.

In any case, the study did not show any convincing evidence of any benefit from acupuncture for dogs with arthritis. Both objective measures (activity monitor and force plate) showed no difference between placebo and acupuncture, as well as no difference between the baseline period and either the placebo or the acupuncture periods. This is a pretty solid negative finding. 

The subjective assessment by the veterinarians also showed no difference between acupuncture and placebo.

Of the subjective measures by the owners, the results were mixed. The overall questionnaire asking owners about effectiveness of treatment at the end of the study showed no difference between placebo and acupuncture. Another subjective measure employed by the owners showed no difference between placebo and acupuncture but did show a difference between the baseline period and the acupuncture period. Finally, yet another subjective assessment did show some difference between both baseline and placebo and the acupuncture treatment.

Inevitably, when multiple measures are used together, some will show a difference and others won’t. Showing a convincing effect requires a consistent pattern of positive results, especially from the more objective measures. Neither of those criteria were met, and the authors acknowledged that, “We rejected our hypothesis because we were unable to detect evidence of differences in the objective outcome measures…However, some treatment response was found using owner completed CMI to assess clinical function and chronic pain. These results should be cautiously interpreted while considering the natural fluctuations in the disease process of OA as well as the caregiver placebo effect.”

Of course, the authors practice acupuncture and clearly believe it is effective, so this is a difficult conclusion to reach. I admire their integrity in acknowledging that the study results did not match h their expectations, though I suspect it is unlikely to shake their confidence in their acupuncture practices. As is often the case in research reports, the authors make some attempt to find explanations for the failure to show an effect other than the most obvious, that the treatment doesn’t work. These include acknowledging that the purported benefits from acupuncture seen in studies of people with arthritis are quite small, considerably less than those from conventional treatments such as nonsteroidal anti-inflammatory drugs, which might mean that any effect from acupuncture might have been swamped in this study by the other treatments the dogs received. This, of course, raises the question of how worthwhile acupuncture is if its effects are so small as to be difficult to see in dogs getting treatments with better supporting evidence of benefit.

The authors also acknowledged that the apparent improvement seen in some dogs from placebo treatment likely represented a caregiver placebo effect. Such effects can, of course, also make therapies like acupuncture look like they work when they don’t in real clinical practice.

Bottom Line
This study found no benefit from acupuncture treatment for dogs with arthritis over placebo (essentially no treatment). Though the methods were not perfect, overall the study was designed, conducted, and analyzed appropriately, and it represents pretty strong evidence against the value  of acupuncture for treating arthritis pain in dogs. Given the lack of strong, compelling evidence in humans despite hundreds of studies over many decades, and the lack of good evidence in other veterinary studies, the most reasonable conclusion at this point is that acupuncture probably has little to no clinical benefit for arthritic dogs. If it is used at all, it should be as an adjunct, not a primary, treatment and only with full disclosure to owners about the likelihood that it is nothing more than a placebo.