I have been trying to keep up with the clinical trial literature evaluating cannabis (primarily CBD) in veterinary patients. There is a lot of research happening right now, so it is challenging to keep current even on this limited subset of studies, but fortunately I know some folks who are much more involved with CBD research and can pass along new evidence as it gets published. So far, clinical trials show promising results for treatment of arthritis pain in dogs and not so promising results in one study evaluating CBD for treatment of canine epilepsy. Another small study looking at treatment of arthritis in dogs (along with some lab animal and human effects) has recently been published which strengthens the case for use of CBD in these patients.
Verrico CD, Wesson S, Konduri V, et al. A randomized, double-blind, placebo-controlled study of daily cannabidiol for the treatment of canine osteoarthritis pain [published online ahead of print, 2020 Apr 24]. Pain. 2020;10.1097
This study included a relatively small number of dogs (20) divided into 4 groups: placebo, two different doses of plain CBD, and a type of CBD packaged chemically into little globules called liposomes, which can influence how some drugs are absorbed and distributed in the body. The study used subjective assessment of arthritis symptoms by both veterinarians and owners, and both groups were blinded to the treatment each dog received.
The study found statistically significant, and potentially clinically meaningful improvements in most measures for the high-dose and liposomal CBD and no improvement for the low-dose CBD or placebo. The lack of a placebo effect is always a bit of a concern since such an effect is usually seen in pain studies in dogs, and the absence of a caregiver placebo can be a sign of a methodological problem in a study. However, the apparent dose-response, with greater improvement seen at higher dose, is a good sign since this is commonly seen with most pharmaceutical effects. There were no signs of adverse effects or abnormal changes in blood tests.
The non-clinical measures in mice also showed some changes in modulators of inflammation which support a plausible mechanism for clinical effects, a necessary step in building an overall picture of the value of any drug therapy.
While this is a small study, and no single trial is sufficient to make a definitive judgment, this is good quality evidence which is consistent with other existing studies, and it strengthens the case for CBD as a potential treatment in dogs with arthritis. All of the usual caveats apply- this doesn’t support any of the hundreds of other claims for CBD; many over-the-counter CBD products have uncertain ingredients and poor quality control, so even if CBD has real benefits they may not be seen with poorly regulated products; there is stronger evidence for the benefits and potential risks of NSAIDs, and these are still a first-line treatment for arthritis in appropriate cases, along with weight management and other existing strategies. On the whole, though, the evidence is getting better and better, and the value of CBD for dogs with arthritis seems likely to be quite high.