Guest Post by April Murphy
Cats with Multiple Medical Conditions (kidneys, heart, IBD, liver and more)
The information below was written for the Cats with Multiple Medical Conditions group on Facebook. This is a science-based support group which does not promote or accept the use of untested and unproven therapies for cats. The group post has been reproduced here with the original author’s permission.
OK everyone. It’s time to address the potentially huge issue that is CBD oil. We seem to spend a lot of time reiterating on various posts that we don’t recommend it and that no advice can be given. That still stands; however, we feel it’s time to explain why.
As you are all probably aware, little real research exists into the use of cannabis/hemp/CBD products in cats. We don’t really know what it does, if anything, to help our cats. Some of the claims that are made for relatively low doses are pretty outrageous and have no real backing scientifically. The market is completely unregulated, creating the possibility that many of the currently marketed products for cats may contain something completely other than CBD oil, may not contain enough to have any real effect beyond a placebo, or may in fact contain so much that they are actively dangerous on their own. They may also, in some cases, contain high levels of THC which is also a known toxin for cats. To add to that, there are compounds within CBD oil that are known to potentially be problematic for cats – terpenes are known to cause toxicity in cats, yet are what CBD oil relies on as that is where the allegedly active ingredients are contained. So we have a real potential issue there before we even get any further into the science of how the body processes CBD.
Next, we have to look at how CBD is processed in the body. We see recommendations on an almost daily basis that state that separating CBD oil from other meds by 2 hours will make it all safe and that there won’t be any interactions with other prescribed meds. However, none of the available evidence backs this up. Cannabis compounds are detectable in human urine up to 30 days after last use. Even if we assume that cats metabolize twice as fast as humans (and that’s not necessarily an accurate number although does appear to work for some medications like insulin), that means that CBD oil is active in a cat’s system for around 15 days…as long as the Convenia shot that so many refuse to consider for their cats due to it’s longevity in the system. And for all of that time, it has the potential to cause drug interactions. Separating it from other meds by just 2 hours is, honestly, a pointless exercise given that information.
Cannabis/hemp compounds, including CBD are cleared from the system using the cytochrome P450 mechanism. Unfortunately, the majority of commonly prescribed drugs are also cleared using this same mechanism. This means that, given that CBD is a strong P450 inhibitor (increasing concentrations of other drugs more than five-fold, while potentially decreasing clearance rate by 80%), there is a very real risk of a cat being overdosed on their prescribed meds if CBD oil is given concurrently. And by concurrently, I mean within days of the prescription meds given how long CBD lasts in the system. To give just one example, if you then add in a dose of amlodipine which is both processed by cytochrome P450 AND further inhibits it, you could find the situation where the cat actually has active levels of more than 100% higher than intended in its system – and those levels could very easily take days to clear…by which time more doses have been added potentially leading to a life threatening overdose over the course of several days/weeks. Many types of anesthesia drugs are also processed by the P450 mechanism – do we really want to take the chance that a cat is either overdosed on anesthesia should an emergency surgery be required, or that they cannot clear the anesthesia drug from their system following surgery?
On yet another note of caution, using cannabis compounds when there is kidney, liver, cardiovascular disease or any degree of immune system suppression is not recommended. There is potential evidence that these compounds can actually cause renal issues…not something we want for our cats who are already prone as a species to kidney failure.
In light of all of this, and pending further research, we have to take the decision that we cannot allow CBD oil to be recommended currently within the group. We cannot permit dosing recommendations to be given for it, especially in conjunction with any other medications. If your vet is prepared to make a recommendation then you are, of course, free to follow it but there is not enough information currently available for us to be able to offer any advice or help with its use.
Update July 9th, 2019 – this is an article about some new research that shows the potential for liver damage even without the addition of other meds as well as the CBD oil. https://www.forbes.com/sites/mikeadams/2019/06/18/marijuana-study-finds-cbd-can-cause-liver-damage/#7060739a43ff