There are some fundamental distinctions one must make on the topic of medical cannabis, and even certain terminology used when approaching medical cannabis as a valid medical therapy. The first distinction is between a “marijuana” plant versus a “hemp” plant. The marijuana plant with its several subspecies is in the same gene pool as the hemp plant but has been purpose bred for higher levels of delta-9-tetrahydrocannabinol (THC), the psychoactive agent people seek to get “high.” Whereas, the hemp plant has much lower levels of THC (less than 0.3%) and has been used for thousands of years as a medicine, fiber, and other for industrial purposes.

The use of marijuana and hemp plant components in veterinary medicine is growing rapidly. Unfortunately, it is growing faster than most practitioners (veterinarians and nursing staff) can educate themselves with scientifically based studies. Because cannabis is still commonly used and thought of as a recreational drug, it is difficult for many medical practitioners to accept the idea of using components of this plant species, especially without FDA regulation or approval. This implicit bias, the confusing legal issues and the many misconceptions surrounding recreational marijuana, turned Cannabis Renaissance are perpetuated by confusing advertising of medical cannabis which uses marijuana/hemp leaves, bringing to mind images of bongs, joints, giggle attacks while eating a cheeseburger, or three…thereby perpetuating this implicit bias. Since the legalization of medical marijuana in the states began the Animal Poison Control hotline has seen a 330% increase in THC toxicities. There is no question to the risk and occurrence of THC toxicity in animals. However, THC is not a part of the conversation for these proceedings. It should be stated there are no reported deaths (animals or humans) that can be distinctly attributed to THC or other phytocannabinoids without other factoring chemicals also present in the system. The suspected lethal dose of THC in dogs is >9 g/kg, a nearly impossible dose to achieve.

We now have the results from three studies, one conducted at Colorado State University, one sponsored by GW Pharma and another sponsored by ElleVet Sciences at Cornell University to help shed light on effective and safe dosing of CBD products. Data has shown in both studies that the other non-psychoactive cannabinoids, primarily CBD, has a wide safety margin with only minimal side effects. In the study conducted at CSU, diarrhea was common in research cohorts, along with an elevated ALP. Interestingly, the increased liver value was not associated with any other elevated liver values (GGT, Bile Acids or ALT) and it may be a response to cannabinoid metabolism through the CYP450 pathway. Moreover, the dose used in the study was significantly higher than what the leading cannabis experts and final conclusions will recommend.

The data out of Cornell suggests a 2 mg/kg dose BID for the product they used, made by ElleVet Sciences. We also know these products are safe to use with NSAIDs, gabapentin, opioids, amantadine and can even lower the dose required of each. Research in cats is limited with ElleVet leading the way with PK and clinical study showing good safety and efficacy thus far. Auburn University’s College of Veterinary Medicine has developed an assay that can detect different cannabinoids present in the blood of dogs and horses for efficacy and safety testing. Dr. Wakshlag of Cornell University even stated in a memo that ElleVet’s industrial hemp product was "efficacious for pain in dogs with osteoarthritis, chronic joint pain and geriatric pain and soreness; with dramatic beneficial effects in our more geriatric patients."

Every creature’s physiology strives to maintain homeostasis; however, trauma and disease can interrupt this process. Phytocannabinoids, more specifically CBD, are excellent in the neurotransmission of the ECS and strive to keep the body as homeostatic as possible. When we use molecules that create homeostasis by facilitating either upregulating or downregulating homeostatic systems, we rarely see negative consequences. Most pharmaceuticals we use in practice only up- or downregulate a system. Hence, we see potential side effects. While veterinary research continues to find the scientifically based dosing and full potential of efficacy.

When dosing, we must consider all of the plant derived products are dynamic and no two will be exactly alike. The ECS is also dynamic and each patient will respond differently. It is ideal to start with a low dose and increase to the desired effect over time.

This blog is based on the proceedings of Stephen Cital's session 'An Appropriate Approach to Medical Hemp' at Chicago Vet 2019.