The plant cannabis, which provides both hemp and marijuana, has a complex chemical makeup. Besides providing many practical products in the hemp form, it contains more than 100 “cannabinoids.” These are psychoactive chemical compounds, i.e., they affect the brain.  A major compound is cannabidiol, or CBD.

Some people recommend CBD oil for senior dogs. This is with the intent of treating symptoms of canine cognitive dysfunction, anxiety, and more. Please be aware that in doing so they are making a medical recommendation. If they don’t have veterinary credentials, this is against the law in most countries. The Food and Drug Administration in the U.S. regularly warns the companies selling CBD oil for people and dogs that they must not market them as medications. The list below will tell you why.

Here are some reasons to think twice about adding CBD to your senior dog’s meds.

1. CBD oil has not been tested as a treatment for dementia in dogs. This one reason should be enough. Do you want to experiment on your dog with a substance that may affect their brain? Research on the many compounds from the cannabis plant is still in its infancy. There has been some progress, but it hasn’t gotten to dogs yet. So far, there are findings that CBD may provide mild help for humans with chronic pain, pain from multiple sclerosis, and with nausea from chemotherapy. There are indications that it might help with epileptic seizures. However, a recent review study showed that there is no evidence that cannabinoids help with human dementia.

But even if there were evidence for CBD helping humans with dementia, we couldn’t assume that it works for dogs. Some helpful drugs and supplements for humans are actually toxic to dogs.

There are several clinical trials with cannabis going on for dogs. One is for dogs with epileptic seizures. It does look promising.  Here is an article about the initial study. The researchers are currently recruiting participants for a subsequent study to determine a dose that is both effective and safe.

The two other studies, both for joint pain and arthritis, are through Cornell University and Colorado State.

One peer-reviewed study published recently reported the testing of CBD for noise-induced fear in dogs. The CBD was used by itself and in combination with the prescription drug trazodone. The CBD failed to show any fear-reducing or relaxing effects, and it actually appeared to lower the efficacy of the prescription sedative trazodone when used in combination.

Colorado State University is currently recruiting participants in a clinical trial that does include testing CBD’s effects on canine cognitive dysfunction. The study is enrolling participants through December, 2030, so results of this study are a long way off.

2. Quality control for CBD products is poor. Some products advertised as having CBD oil don’t have a trace of the oil in them at all. Some products were contaminated with other compounds.  The ones that do have it contain hugely varying amounts compared to each other. Here are the warning letters sent out by the FDA in 2015, 2016, and 2017 to CBD oil companies in violation of the law. They received the warnings because there was no CBD in the product, there was contamination with other substances, or because they made illegal claims. Buyer beware!

3. Safe dosages have not yet been determined. This is an offshoot of #1 but merits its own section. We often don’t realize all the things research needs to tell us. When a substance is studied, the research goes far beyond whether it “works.” It has to be determined whether the substance has any adverse effects or drug interactions (see #4). Dosage needs to be figured out. Some cannabinoids are toxic to dogs at certain dosages.  For instance, this article reports the deaths of two dogs from marijuana-infused butter.  Here is a large study of the toxic effects of marijuana (not CBD) in dogs. While cannabidiol is thought to be less toxic than some other compounds in marijuana, there is still a risk from amounts or contaminants, especially if you are buying from a company who has been cited in the past.

4. Interactions with other drugs and supplements are unknown. Senior dogs, with or without dementia, are sometimes on several medications and/or supplements. Veterinarians keep our dogs safe from negative effects because they know about drug interactions. With the exception of the one study mentioned above that showed an undesirable interaction with trazodone, the statistical information for CBD simply isn’t there yet.

5. Drugs that affect the brain and neurological system affect individuals very differently. Don’t forget: CBD oil affects the brain. Many psychoactive drugs have different effects on individuals. This is true for people and for dogs. Many people have to try several different antidepressants before finding one that works. The “wrong” antidepressant can make depression worse.  Likewise, my fearful dog who takes medication didn’t do well on the first one we tried but did on the second. It’s unlikely that there is a “one size fits all” solution with this kind of drug.

6. When we try a remedy, we tend to be biased about it. We all want to believe that we are free from bias, but it is a hard thing to achieve. When we invest our time and money on a solution for a beloved dog, we desperately want it to work. There is a specific bias that pops up easily in this situation called “regression to the mean.” The way this works is that many diseases and conditions have symptoms that come and go, get worse, then better again. We typically look for help when our dogs are going through a hard time. Then whatever intervention we have chosen is likely to look effective. This is because what naturally happens after the symptoms have bottomed out for a while is that the dog gets better (for a while). Then we attribute it to the therapy we started, when actually there may not have been any relationship at all. Besides regression to the mean, there is also the placebo effect. Not for the dogs, but for the people. When we give medications, we believe they work, even if the evidence doesn’t necessarily say so. This has been shown to happen to dog owners and even vets regarding whether a certain medication worked.

For more information on how our brains are automatically biased in certain situations, check out Kahneman’s book, Thinking Fast and Slow. It has many, many examples.

Natural Treatment of Canine Cognitive Dysfunction

Many natural remedies and supplements are available that claim to help dogs with dementia. But only a few have been shown to work in clinical studies. Check out the treatment page on this blog for a list. And most important, talk to your vet before even considering trying these supplements. Supplements are made of chemicals, just like prescription drugs, only are much less controlled. Supplements can interfere with each other and with prescription medications. Only your vet can tell you if they are safe for your individual dog.

But It Worked for My Dog!

As noted above in #6, most of us are hopeful when we try a new treatment for ourselves, a human loved one, or our dog. What usually happens, because of regression to the mean and confirmation bias, is that we perceive a benefit right away. Then it seems to dwindle. How many times have you seen someone report, “This treatment helped at first but it’s not helping anymore.” It may not have been helping at all; it could just appear to help from the timing.

If you are serious about testing a medical intervention or supplement for dementia, work with your vet. And be sure you keep a journal of your dog’s symptoms starting before you give them the treatment. That will give you an objective measure as a benchmark to help you determine whether your dog is actually improving.

Copyright 2018 Eileen Anderson

Photo Credits

Green vials photo from Canstock photo.
Capsules photo copyright Eileen Anderson.
Cannabidiol molecular diagram courtesy of Wikimedia Commons and can be found here.
Two photos of dried cannabis courtesy of Wikimedia Commons and can be found here.

Further Reading

This blog by a credentialed veterinarian tracks the claims and progress made about using cannabis on pets. Here is his latest article, and note it links to an earlier one. He is good to follow because he will update the info as research becomes available.

Resources

Colorado Researchers Studying CBD Oil In Dogs.  Retrieved from  http://denver.cbslocal.com/2018/05/18/colorado-cbd-oil-dogs/

Conzemius, M. G., & Evans, R. B. (2012). Caregiver placebo effect for dogs with lameness from osteoarthritis. Journal of the American Veterinary Medical Association, 241(10), 1314-1319.

Devinsky, O., Cross, J. H., Laux, L., Marsh, E., Miller, I., Nabbout, R., … & Wright, S. (2017). Trial of cannabidiol for drug-resistant seizures in the Dravet syndrome. New England Journal of Medicine, 376(21), 2011-2020.

Efficacy of Cannabidiol for the Treatment of Epilepsy in Dogs  retrieved from http://csu-cvmbs.colostate.edu/vth/veterinarians/clinical-trials/Pages/efficacy-of-cannabidiol-for-the-treatment-of-epilepsy-in-dogs.aspx

Ellevet Sciences: For Veterinarians. Information on clinical trial for osteo-arthritis and joint pain treated with CBD oil. Retrieved from https://ellevetsciences.com/pages/for-vets

Janczyk, P., Donaldson, C. W., & Gwaltney, S. (2004). Two hundred and thirteen cases of marijuana toxicoses in dogs. Veterinary and human toxicology, 46(1), 19-20.

Kahneman, D. (2011). Thinking, fast and slow. Macmillan.

Krishnan, S., Cairns, R., & Howard, R. (2009). Cannabinoids for the treatment of dementia. The Cochrane Library.

Machado Rocha, F. C., Stefano, S. C., De Cassia Haiek, R., Rosa Oliveira, L. M. Q., & Da Silveira, D. X. (2008). Therapeutic use of Cannabis sativa on chemotherapy‐induced nausea and vomiting among cancer patients: systematic review and meta‐analysis. European journal of cancer care, 17(5), 431-443.

Martín-Sánchez, E., Furukawa, T. A., Taylor, J., & Martin, J. L. R. (2009). Systematic review and meta-analysis of cannabis treatment for chronic pain. Pain medicine, 10(8), 1353-1368.

Meola, S. D., Tearney, C. C., Haas, S. A., Hackett, T. B., & Mazzaferro, E. M. (2012). Evaluation of trends in marijuana toxicosis in dogs living in a state with legalized medical marijuana: 125 dogs (2005–2010). Journal of Veterinary Emergency and Critical Care, 22(6), 690-696.

Morris, E. M., Kitts-Morgan, S. E., Spangler, D. M., McLeod, K. R., Costa, J. H., & Harmon, D. L. (2020). The Impact of Feeding Cannabidiol (CBD) Containing Treats on Canine Response to a Noise-Induced Fear Response Test. Frontiers in Veterinary Science, 7, 690.

National Academies of Sciences, Engineering, and Medicine. (2017). The health effects of cannabis and cannabinoids: The current state of evidence and recommendations for research. National Academies Press. Retrieved from https://www.nap.edu/read/24625/chapter/1

Skeptvet Blog: “Presentation on Cannabis for Pets.” Retrieved from  http://skeptvet.com/Blog/2018/03/presentation-on-cannabis-for-pets/

Thompson, G. R., Rosenkrantz, H., Schaeppi, U. H., & Braude, M. C. (1973). Comparison of acute oral toxicity of cannabinoids in rats, dogs and monkeys. Toxicology and applied pharmacology, 25(3), 363-372.

US Food and Drug Administration. (2017). Warning letters and test results for cannabidiol-related products. Retrieved from  https://www.fda.gov/NewsEvents/PublicHealthFocus/ucm484109.htm