by E. Mironchik-Frankenberg, DVM.
As a cannabis educator and writer, much of my time is spent researching this hotly debated topic. During the countless hours spent reading publications about cannabis and pets, I am always dismayed to read unqualified statements such as “THC is toxic to dogs” or “Avoid products containing any THC.” These statements are misleading and, at the very least, need to be clarified. To make this claim without any qualification or description only leads to confusion. In fact, in a recently published veterinary research paper, the author specifically stated “THC is toxic to dogs” in the introduction, and yet, the product utilized in the study contained THC.10 Clearly, this hypocrisy, whether intended or not, needs to end. The constant mislabeling of THC as ‘dangerous’ has led many to believe that this compound is poisonous and that the smallest amount will kill their pet. THC is, in fact, vital for the complete entourage effect that is unique to cannabinoid medicine. Therefore, I would like to try and dispel some of the constantly perpetuated myths surrounding THC in pets, the pros and cons, and how we can best move forward.
What is THC?
THC, or tetrahydrocannabinol, is the most well-known cannabinoid in modern cannabis and is often defined as the ‘main psychotropic component’ of the cannabis plant. THC is the cannabinoid most responsible for the intoxicating effects of cannabis, the reason for its widespread and centuries long use as a recreational drug, and consequently, the reason for its federally illegal status as a potential drug of abuse. While these points are widely accepted, they do not negate the fact that THC is also an important medicinal cannabinoid as well. Since the early days of scientific exploration of this plant, a long list of medicinal qualities of THC have been elucidated, and we are still discovering new beneficial uses, ranging from analgesia to anti-cancer effects. 7
This cannabinoid can have profound effects on any species with an endocannabinoid system (ECS), both human and animal. It’s wide ranging physiological effects, are largely the result of its interactions with the cannabinoid receptors, as well as other biological systems within the body.
What does this mean for pets? What does toxicity look like?
Humans and various animal species respond differently to phyto-cannabinoids, and there is much that is still unknown. What we do know is that the effects observed in pets, especially dogs, are related to the endocannabinoid system and the numbers, amounts and locations of the cannabinoid (CB) receptors, especially the CB1 receptor in the brain. We know less about the ECS in cats, but statistically, they are less likely to suffer from intoxications, simply because they don’t indiscriminately ingest substances they encounter in the same way dogs often do.
Cannabis is extremely safe for people, as there has never been a reported death due to ‘overdose’ of cannabis for human beings.15 This is due to the location of the CB receptors in the human body and the fact that there are none located in the respiratory control centers of the brain. That is why, as opposed to opioids, cannabinoids do not cause fatal consequences by depressing respiration.
In our pets, there are some differences in the locations of these CB receptors and as a result, differences in the effects of THC on their bodies. An important point for pet parents to understand is that the canine is the species that has the MOST CB1 receptors in the cerebellum (the area of the brain responsible for balance and coordination), and is consequently, the most sensitive to the effects of THC.2,3 For this reason, excessive stimulation of these receptors leads to adverse effects relating to functions controlled by this region of the brain. That is why, when they receive too much THC, dogs suffer from a unique set of symptoms known as “static ataxia.”4 Symptoms of this condition typically manifest as one or more of the following:
- Severe ataxia (incoordination) and stupor
- Drooling
- Rocking side to side with a wide based stance
- Glazed over eyes, dilated pupils
- Urine dribbling
- Falling over
- Changes in heart rate or temperature
- In severe cases… vomiting, seizures, other neurologic effects12
When a dog presents to the clinic in this manner, most experienced veterinarians are quick to recognize the symptoms. The above signs can vary depending on the dose of THC the dog was exposed to, as well as size, age, and any other underlying medical conditions present. Treatment is generally supportive (maintaining hydration, body temperature, etc.), but may require hospitalization and closer monitoring if the signs are severe, lasting from 1-3 days on average. The majority of dogs that suffer from this type of adverse event recover completely with basic supportive care and no long-term side effects.12
It is important to note that the severity of clinical signs is dependent on the amount of THC the dog was exposed to. When the above adverse effects are seen, it is due to very high doses of THC, usually via accidental ingestion of human products. THC has a reported wide safety margin in dogs- a dog would have to ingest approximately 3000mg/kg to reach the suspected minimum lethal oral dose. This dose is 1000 times the THC dosage where behavioral effects are observed.12 To compare, this is analogous to the fact that a single pill of carprofen ( a commonly used veterinary nsaid) is effective for relieving your pet’s pain, however, if the pet accidentally ate the entire bottle of pills, it would end up in the ER with signs of toxicity. Veterinarians rightly focus on the beneficial effects of carprofen, not the potential for adverse signs when an accidental overdose is given. I would argue that we need to approach THC in the same way. If given in a safe, cautious manner, the above situation can be avoided!
Why would we want to use THC in our pets?
Given the information above, why and how would we want to use THC in our furry children? I would argue that there are situations in which THC, when used judiciously, can be of enormous benefit in our pets. For example, the pet with severe pain that is uncontrolled by traditional medications or CBD-only products, the cancer patient suffering from the effects of the disease, as well as the side effects of traditional chemotherapy drugs, or the pet with severe inappetence that will not take any food willingly. These are all situations where THC may be helpful, and the benefits may outweigh any potential risks.
There is sound, scientifically based evidence to support the argument for the added benefit of THC in the medicinal use of cannabis.7
–The “entourage effect.” This concept refers to the synergistic activity and increased medicinal benefit and safety when using whole plant products, those that contain all the active medicinal components from the plant. Numerous studies have shown that using cannabis in this manner results in effects that are far superior to using a product with a single isolated cannabinoid, such as a CBD-only product. In fact, only very small amounts of THC are needed to achieve this end, and CBD acts to modulate the undesirable effects of THC.7,8
-Enhanced potency. Increasing the THC component of the cannabinoid profile in a balanced product increases the strength of the effects. This cannabinoid is more powerful for numerous conditions and its addition can improve the efficacy and duration of the desired clinical benefit.
–Specific clinical indications. THC provides unique effects that cannot be achieved by using cannabis preparations without it. For example, the anti-emetic effects, appetite stimulation, bronchodilatory effects and reduction of intraocular pressure are all largely due to THC and using a product without it is less likely to be successful.
Many practitioners with clinical experience will attest to the benefits of utilizing this powerful cannabinoid. Recently, while discussing this topic with noted veterinary cancer specialist and alternative practitioner, Dr. Trina Hazzah, DVM, DACVIM(O), CVCH, she stated “From an oncology perspective, it is rare that CBD works well without THC, for a sustained, durable response.”
How can the Pet Parent Proceed?
If you believe that your furry family member would benefit from the addition of THC for any of the above reasons, talk to your veterinarian.14 This is an important discussion that you will likely need to initiate. While this path may not be appropriate for all cases, there ARE safe ways to get the medical benefits of THC in veterinary species. The cannabis mantra of “Start Low and Go Slow” is especially relevant when using THC containing products. Experienced clinicians can utilize micro dosing strategies and various methods to slowly build tolerance and minimize the chance of adverse effects.13
Remember THC toxicity can best be avoided by following some basic principles:
- Do not give your pet edibles made for people.
- Do not blow smoke in your pet’s face.
- Do not leave any cannabis products accessible to accidental ingestion by pets (or children).
- Do not try to get your pet “stoned.”
- Any product used must have confirmed amounts of THC, and other cannabinoids, listed in mg strength and verified by an independent lab Certificate of Analysis.
- DO proceed with the guidance and oversight of a licensed veterinary professional.
It is important to remember that this is a decision that ultimately, is up to you, the pet parent. THC containing products from marijuana are still considered Schedule 1 controlled substances by the DEA and no veterinarian can prescribe these products. Pet parents need to choose a quality product and MUST have accurate information about the amount of THC, and other cannabinoids it contains.
Finally, my goal in writing this article is to attempt to clear up confusion surrounding this highly controversial topic. I am certainly not advocating for the indiscriminate use of THC in pets. Instead, I am simply seeking to clarify a few prevalent myths, remove unnecessary fear, and dispel the notion that it is patently dangerous and has no use in animal species. My hope is to change our attitude towards this powerful cannabinoid, so that we can initiate meaningful, productive discussion and advance the important research needed for effective use in our furry family members. I believe we need to shift our stance from “THC is toxic” to perhaps the more qualified position of “THC, if used inappropriately, can result in signs of toxicity…just like any powerful pharmaceutical.” THC should not be demonized, if used in a safe, judicious manner, it holds the potential for profound medicinal benefits, for all species. 😊
** “All information provided above is intended to be educational only and does not represent veterinary medical advice. Please see your pet’s regular medical provider with whom you have a valid veterinarian-client-patient relationship for discussion and treatment. Any discussion of dosing or how to use medial cannabis products is not a legal prescription, recommendation, or endorsement. Use of medical cannabis products in an animal species should only be done after a full examination and discussion with a licensed veterinarian in compliance with all applicable laws.”
References:
2. Herkenham, M., Lynn, A., Little, M., Johnson, M., Melin, L., de Costa, B., & Rice, K. (1990). Cannabinoid receptor localization in brain. Proceedings of the National Academy of Sciences of the United States of America, 87(5), 1932-1936. doi:10.1073/pnas.87.5.1932
3. Freundt-Revilla, J., Kegler, K., Baumgartner, W., & Tipold, A. (2017). Spatial distribution of cannabinoid receptor type 1 (CB1) in normal canine central and peripheral nervous system. PLoS ONE, 12(7). Retrieved from https://doi.org/10.1371/journal. pone.0181064
4. Silver, R. (2015). Medical marijuana & your pet. Lulu publishing.
5. Beaulieu, P. (2005, Feb). Toxic Effects of Cannabis and Cannabinoids: Animal Data. Pain research & management : the journal of the Canadian Pain Society , 10(supp A), 23A-6A. doi:10.1155/2005/763623
7.Russo, E., & Guy, G. (2006). A tale of two cannabinoids: The therapeutic rationale for combining tetrahydrocannabinol and cannabidiol. Medical Hypotheses, 66, 234-246. doi:10.1016/j.mehy.2005.08.026
8. Russo, E. (2019, Jan 09). The Case for the Entourage Effect and Conventional Breeding of Clinical Cannabis: No “Strain,” No Gain. Frontiers in Plant Science. doi:10.3389/fpls.2018.01969
9. Gallily, R., Yekhtin, Z., & Hanus, L. (2015). Overcoming the Bell-Shaped Dose Response of Cannabidiol by using Cannabis Extract Enriched in Cannabidiol. Pharmacology & Pharmacy(6), 75-85. doi:10.4236/pp.2015.62010
10. McGrath, S., Bartner, L., Rao, S., Packer, R., & Gustafson, D. (2019, June 1). Randomized blinded controlled clinical trial to assess the effect of oral cannabidiol administration in addition to conventional antiepileptic treatment on seizure frequency in dogs with intractable idiopathic epilepsy. Journal of the American Veterinary Association, 254(11), 1301-1308. doi:10.2460/javma.254.11.1301
11. Richter, G. (2019, May 1). CBD & Cannabis for Pets in Pain. Retrieved from https://www.projectcbd.org: https://www.projectcbd.org/medicine/cbd-cannabis-pets-pain
12.Fitzgerald, K., Bronstein, A., & Newquist, K. (2013). Marijuana poisoning. Topics in Companion Animal Medicine, 28, 8-12. doi: 10.1053/j.tcam.2013.03.004
13. Hartsel, J., Boyar, K., Pham, A., Silver, R., & Makriyannis, A. (2019). Cannabis in Veterinary Medicine: Cannabinoid Therapies for Animals. In R. Gupta, A. Srivastava, & R. Lall, Nutraceuticals in Veterinary Medicine (pp. 121-155). Switzerland: Springer Nature . doi:10.1007/978-3-030-04624-8
14. https://www.veterinarycannabis.org/starting-the-conversation.html
15. http://druglibrary.org/schaffer/library/mj_overdose.htm
16. Janeczek, A., Zawadzki, M., & Niedzwiedz, A. (2018). Marijuana intoxication in a cat. Acta Veterinaria Scandinavica. Retrieved from https://doi.org/10.1186/s13028-018-0398-0
