Feta Cat’s neurologist suggested that we need to get her leg muscles to relax and loosen up before she will be able to regain strength and, hopefully, use of her remaining back leg.
Among many possible treatments, she suggested “cold laser therapy.” Being a pet owner on a budget, I wanted to know: is “cold laser” therapy supported by legitimate scientific studies, or is it likely to be one more form of medical snake oil marketed to people desperate to feel they are “doing something” to help their pets? (Or, for that matter, themselves – it’s a therapy used in people, too!) Unless it’s quite likely to work, I do not want to pay for it – the money could be better spent on her medication, wheelchair, food, etc.!
Disclaimer: I am not a veterinarian. I do not even play one on TV! I also know that there are important differences between humans and other mammals (and between different species of animals more generally) that cause problems when trying to apply medical findings from one animal to care for another. This is simply a lay-person’s internet research to get a rough idea whether a certain treatment is quackery or may have some therapeutic merit.
Googling on these sorts of topics can be tricky, because a lot of the sources that come up are unreliable – e.g., companies trying to sell you whatever it is you’re researching. So, we approach this carefully.
Also, fair warning: some of the papers do perform research on animals. If this is upsetting for you to read about, I recommend skipping this post!
That said, onwards…
First off, what is “low-level laser therapy” (LLLT) and how does it work? This paper does a great job of explaining the more technical details, though I don’t trust its objectivity in summarizing the data! So, now that we know more or less what it is, let’s see if we can figure out whether or not it works.
One of the best things to do when starting a new research topic is to look for trustworthy research summaries or meta-analyses.
In the case of laser therapy, one place to look is human insurance companies – they tend to be pretty conservative when it comes to treatment and are reluctant to pay for anything that isn’t backed by a large amount of compelling research. On this note, Aetna does not reimburse for laser therapy, saying there is insufficient evidence of its effectiveness. In that statement, they cite a great deal of research to support their decision, and it is a thorough and well-researched summary. Fair enough!
Similarly, a private site devoted to thoroughly researching such claims agrees with Aetna, concluding, “At this writing, the bottom line appears to be that LLLT devices may bring about temporary relief of some types of pain, but there’s no reason to believe that they will influence the course of any ailment or are more effective than standard forms of heat delivery.” (Devicewatch.org, a division of Quackwatch.org)
Those summaries are discouraging, but don’t necessarily say that laser therapy is a scam, simply that there’s not sufficient evidence to draw any firm conclusions. In other words, there’s no significant proof that it does work, but there’s no significant proof that it doesn’t work, either.
With that in mind, I was interested to look at some of the individual research studies / papers.
Again, we start with a meta-analysis (in other words, an analysis of a whole bunch of other analyses; a research summary).
This one concludes, “This meta-analysis presents evidence that LLLT is an effective treatment modality to reduce pain in adult patients with musculoskeletal disorders. Adherence to WALT [World Association of Laser Therapy] dosage recommendations seems to enhance treatment effectiveness.” In other words, this summary suggests that laser therapy works, but works a lot better if you do it as recommended. Fair enough!
This paper – more of a summary than a meta-analysis, I think, though there’s a paywall for the full paper – also suggests that LLLT can be effective for controlling nerve pain. However, this paper rightly points out that there is a lot of variation in treatment protocols, so more work is needed to determine which wavelengths, treatment frequencies, etc. are the most effective.
Of note: just because something is a meta-analysis doesn’t mean it’s “right” or unbiased. All sorts of decisions go into a summary or meta-analysis, from which studies to include to how to weight the findings. As a result, we sometimes see contradicting meta-analyses on the same topic! Still, going for a summary of a lot of different researchers’ work is more likely to be helpful than relying on one single paper.
Next I wanted to look at a couple of sample individual papers.
These were not selected systematically, but were just ones that seemed relevant, recent, and came up from my first search of PubMed.
This study suggests that laser therapy can reduce pain sensitivity and decrease inflammation in rats that have constriction-related nerve pain (you can think of it as animal sciatica – something is pinching the nerves and causing a lot of pain). For our needs, and especially for mine with Feta and Rascal’s intervertebrate disc compression, this is very relevant!
Similarly, this study found that LLLT improved regeneration of the sciatic nerve as well as the animals’ ability to move normally.
Also note: beware the “file drawer effect”!
What do I mean by this? Basically, scientists are (unfairly, in my opinion) rewarded much more for studies that find a significant effect of something. This is for a number of reasons. You can imagine that you are trying to prove that eating sticks of butter leads to gaining weight. All you need is one good study that DOES show an effect – people who eat sticks of butter gain more weight – to suggest that an effect is there. To think of it another way, all you have to do is see Bigfoot one time, up-close and personal, with very little doubt that it is ACTUALLY Bigfoot, and you’re a Bigfoot Believer!
When research shows a null result, however – essentially, you try one thing and it doesn’t seem to work – there are a million reasons why that could be. If you do a study and find that people who eat sticks of butter DON’T gain more weight, does that mean that butter isn’t fattening? No, of course not. You could have measured poorly. You could have measured at the wrong time. You could have not controlled for some important other influence (what if the butter-eaters were also running marathons every day?). You can’t definitively prove the absence of something. If you go out into the woods for a month and do not see Bigfoot, does that mean he doesn’t exist? Not necessarily. You probably won’t see any snow leopards, either, but other people have some very convincing evidence that snow leopards are, in fact, a thing.
So, when scientists do not find evidence of a thing, people don’t usually get very excited. It’s generally harder to get the research published, and it’s not very beneficial to the scientist’s career. Since it takes a lot of time and effort to get something published, these “null result” studies often go unreported, hanging out in the “file drawer” for a “maybe some day I’ll get around to it” type of publication. In other words, we’re more likely to see papers that do show an effect compared to those that don’t show the effect, but that could be largely due to publication bias. Those “null effect studies” may exist, just not be published.
So, what’s the laser verdict?
Overall, there seems to be very little consensus on the “best” laser dosage and wavelength to use. This makes it difficult to compare across studies, since every one is doing something a little different!
My take-home is essentially: laser therapy may be helpful, but it’s far from guaranteed to work.
So, my totally lay person advice? If you can afford it, go for it. It won’t hurt and may help! However, if you’re on a tight budget, you may be able to skip the laser therapy for some quality at-home time with a heating pad, and save the money for other treatments that are more certain to be effective (e.g., time swimming, physical therapy exercises, medicine, etc.). This is, obviously, something to talk over with your vet and/or veterinary physical therapist! They may have their own biases – medical professionals are people, too, and are just as likely as the rest of us to do things like selectively remember what supports their beliefs while forgetting what contradicts them – but if you have someone whom you trust to help your pet, it’s always a good idea to talk to them honestly about your concerns as well as your finances!
Hope this long diatribe has been helpful – either for assisting others in making an informed decision about cold laser therapy or, more likely, for helping some folks fall asleep 😀
