As a cannabis educator and writer, much of my time is spent researching this hotly debated topic. During the countless hours I spend 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.
For example, in a research paper recently published in the Journal of the American Veterinary Association, the author specifically stated “THC is toxic to dogs” in the introduction, despite the fact that a test product used in the study, which contained THC, induced no signs of toxicity. Clearly, these contradictory messages, whether intentional or not, need to end. What are pet parents to think? The decades-old attitude of fear surrounding THC needs to change. The constant labeling of THC as “dangerous” has led many to believe that this compound is poisonous and that the smallest amount will kill their pet.
But as many medical professionals know, THC is not evil and is, in fact, vital for the complete entourage effect that is unique to cannabinoid medicine. Therefore, I would like to try to dispel some of the constantly-perpetuated myths surrounding THC in pets, its pros and cons, and how we can best move forward.
THC, or tetrahydrocannabinol, is one of the most abundant cannabinoids in modern cannabis and is often defined as the “main psychoactive 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 considered an important medicinal cannabinoid by many doctors and scientists. 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, as reported in a 2006 research paper published in the journal Medical Hypotheses.
This cannabinoid can have profound effects on any species with an endocannabinoid system (ECS), both human and animal. Its wide-ranging physiological effects are largely the result of its interactions with the ECS’ cannabinoid receptors and other biological systems within the body.
Humans and various animal species respond differently to phytocannabinoids, 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 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 in a human being (according to a 1971 study, a person would need to eat approximately ⅓ of their body weight in cannabis for the effects to be fatal). 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, according to research published in the journal PLOS ONE.
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.” Symptoms of this condition typically manifest as one or more of the following:
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 the animal’s 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.
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 3000 mg/kg to reach the suspected minimum lethal oral dose. This dose is 1,000 times the THC dosage where behavioral effects are observed, according to a 2013 article in Topics in Companion Animal Medicine
To compare, this is analogous to the fact that a single pill of carprofen (a commonly used veterinary anti-inflammatory drug) 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.
Given the information above, why and how would we want to use THC in our pets? I would argue that there are situations in which THC, when used judiciously, can be of enormous benefit in our pets. For example, consider 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, much of which is based off the work of cannabis researchers Dr. Ethan Russo and Dr. Geoffrey Guy.
The “entourage effect”: This concept refers to the synergistic activity and increased medicinal benefit and safety when using whole plant products, which are 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.
Enhanced potency: Increasing the THC component of the cannabinoid profile in a balanced product increases the strength of the effects. This cannabinoid is a powerful tool useful for numerous conditions (such as severe pain) 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.”
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. 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.
Remember, THC toxicity can best be avoided by following some basic principles:
It is important to remember that this is a decision that ultimately, is up to you. THC-rich products derived from marijuana are still considered Schedule 1 controlled substances by the Drug Enforcement Administration (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. For those needing assistance in making this choice or in navigating any part of this process, there are resources available. To get started, talk to an experienced veterinary cannabis counselor at www.veterinarycannabis.org.
Finally, my goal in writing this article is to attempt to clear up the 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 companion animals. 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 on cannabisMD 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.”