It’s been a long-held notion that cannabis – and its many forms and derivatives, including cannabidiol (CBD) – can function as a medicine, or even cure, for various ailments. And not just in humans, but in animals, including dogs, too.
One illness where cannabis is often lauded as a curative treatment is canine arthritis. There are many anecdotal stories out there of people ‘curing’ their dog’s arthritis with nothing but cannabis or CBD, shunning standard treatment in favour of this ‘wonder’ plant.
But what – if any – evidence is there to show that cannabis or CBD is an effective treatment for arthritis in dogs?
The short answer to the question ‘does CBD or any other cannabis-derived substances cure arthritis in dogs’ is ‘no’.
But the slightly longer, and perhaps more accurate answer, is, ‘based on the evidence we have right now, no’. Because with science, we can rarely definitively say ‘no’ to questions like this; instead we base our answers on the evidence that’s currently available.
In the case of CBD / cannabis and arthritis in dogs, that evidence is sparse to say the least. So far, there appears to be only one published, peer-reviewed scientific paper that describes a study looking at specifically CBD as a treatment for this illness.
The study, carried out at Cornell University College of Veterinary Medicine, aimed to determine the dose and safety of CBD-based oil in dogs with osteoarthritis (OA), and to test how well it worked at alleviating pain caused by the disease.
To do this, they first tested two doses of CBD (2mg/kg and 8mg/kg) and found that 2mg/kg was the preferred dose. In the second stage of the study, they recruited 22 dogs onto a clinical trial to test if CBD-based oil alleviated any arthritis symptoms. Of the 22 dogs, 16 completed the study.
Some dogs were given the CBD-based oil, while some were given a placebo comprised of anise and peppermint oil, mixed with olive oil. Neither the vets involved in the study, nor the dogs’ owners knew if their dog was receiving the placebo or the CBD-based oil. This is done to reduce the risk of introducing bias to the study.
All dogs – irrespective of whether they got the drug or placebo – received treatment twice a day (every 12 hours) for 4 weeks, followed by a 2-week wash-out period, which means the drug was given time to leave the system. The effects – if any – of treatment were measured by comparing pre- and post-treatment levels of:
- Serum chemistry
- Physical examination
- Changes in pain levels, based on:
The results of the study showed that there were no apparent side effects (major or minor) from the use of CBD-based oil in dogs with OA. And that by all measurement parameters and methods used, there was a significant decrease in pain and an increase in activity in those dogs with OA who received the CBD-based oil, compared with dogs who received the placebo.
Overall, the study suggests that giving 2mg/kg of CBD-based oil, twice a day, can help alleviate the symptoms of OA in dogs, and improve their quality of life.
Good news right? Well yes. And no.
While on the surface of it this paper seems like the proof everyone has been waiting for that cannabis / CBD-based oil is an effective treatment of arthritis in dogs, it’s not that straightforward.
While this certainly is a strong study, it isn’t without its limitations and issues, of which the main ones are listed below.
The study began with 22 dogs enrolled, which in itself is quite a small sample size, and is too small to draw any broad, general conclusions from. This is because studies with small samples sizes can be prone to producing unreliable results.
On top of this, the study explains that not all 22 dogs actually took part in or completed the study – that number was actually 16. To say, based on a study which only included 16 dogs, that CBD-based oil is an effective treatment for OA in dogs would be at best, inappropriate and controversial. At worst, it would be dangerous. Put simply, this is too small a sample size from which to extrapolate recommendations for the canine wider population.
Breed and gender:
This study primarily enrolled large breed dogs (eg Rottweiler, Bernese Mountain) and of the 16 dog who completed the study, 10 were female (~2/3). It’s also worth noting that some dogs were spayed and castrated, while others weren’t.
Having an unequal split of male and female dogs, a mix of neutered and non-neutered dogs and predominantly including large dog breeds in the study is less than ideal. Because while it doesn’t necessarily impact on or bias the results, it does again mean that we’re limited in the conclusions that can be drawn from the study and in who the results could be applicable to.
The aim of a placebo is to ensure that those who don’t receive the treatment being tested don’t know they’re not getting it. In doing this, it helps to remove any bias that trial participants might inadvertently display.
For example, if someone knows they’re getting the drug being tested, they may be more like to report a positive effect from it. While if someone knows they’re not getting the drug, they may report no change in their symptoms, even if there is.
For these reasons – to avoid any bias – it’s important that a drug placebo look, taste, smell and feel as similar to the drug being tested as possible. In this study, the authors made a good effort with the placebo that they created. However, they don’t report how effective their placebo was, in that we don’t know if any of the vets or dog owners in the study suspected they were receiving the placebo.
It is a small limitation of the study, but it is one none the less. CBD-oil has a distinctive smell and so effectively mimicking that in a placebo could be difficult. And if not done properly, this could unconsciously bias the placebo group to reporting no change in pain alleviation, meaning the results would be skewed.
Length of study:
This trial ran for four weeks, with a two week wash out period, meaning participants were given the CBD-oil (or placebo) twice a day for 4 weeks.
While a clinical trial cannot carry on indefinitely, 4 weeks is also quite a short amount of time to run a trial testing the efficacy of a drug. Not all dogs will respond to a treatment in the same way as they have different metabolisms etc. This means that some dogs may need to take a drug for longer before any benefits are seen. In this way, they study may have sold themselves short as more of an effect may have been seen over a longer testing period.
Equally, testing for such a short period of time tells you nothing about the effects of long-term administration of CBD-oil to dogs with arthritis. While no major side effects were reported by owners or vets over the 4-week period, this doesn’t mean CBD-oil doesn’t cause long-term side effects that may materialise at a later date. And in the study, the authors note an increase in alkaline phosphatase levels in those dogs receiving the CBD-oil, something which may cause damage if it continued over a long period of time.
And on side effects, it is interesting that this study reports no side effects what-so-ever in the dogs taking CBD-oil. In any human trials of cannabis or CBD that have taken place, there has been a relatively high, consistent rate of minor side effects reported, including some that limit tolerability of the CBD-oil by the patient.
The lack of side effects reported in this study could be a minor cause for concern as it could mean:
- the CBD-oil wasn’t actually doing anything at all; that is the treatment wasn’t having any affect on OA or its symptoms
- the study wasn’t properly designed to pick up any side effects that may actually exists. This also links to the small sample size used in the study – there may well have been no side effects in this group of dogs, but that doesn’t necessarily mean there won’t be any side effects at all in a wider population
So, what does all of this mean? In short, this study is a good one, which while it does have its limitations, is still sound in its approach to testing the efficacy of CBD-oil as a treatment for OA in dogs. However, while it does have its strengths, it also has its limitations, including those described above.
This means that while the findings of this study are interesting, they should be treated as a starting point from which further studies can and should be carried out to determine if CBD-based oil can be used to treat OA in dogs and alleviate the diseases symptoms.
It does not mean that everyone with a dog who has OA should stop administering the existing treatment (typically NASIDS), because right now, we simply don’t know enough to say that this would be the best thing for your dog.
With more research, CBD-based oil, and indeed other cannabis-derived products, may prove to be the best, most effective, non-toxic, non-side effect inducing treatment for dogs with OA.
But we cannot say this right now – there simply isn’t enough strong, robust science to support the claim. For now, the absolute best thing to do for your dog if they have OA – or any form of arthritis – is to speak to your vet and a qualified canine dietary consultant about the best available treatment for them.
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