Rob Silver, DVM
Dr. Rob Silver is an adjunct faculty member at Lincoln Memorial University College of Veterinary Medicine in Harrogate, Tennessee, president-elect of the American College of Veterinary Botanical Medicine, founding member of the Veterinary Cannabis Society, and a member of the Society of Cannabis Clinicians.
Those of us who work in the hemp industry can get a little zealous about the benefits of the cannabis plant. After all, it's been part of human civilization for centuries, and it's certainly important to American history. The Revolutionary War was fought at least in part over hemp because of its value as a fiber for rope, clothing and ships' sails. The first U.S. flag was made of hemp cloth. Henry Ford fashioned the first Model T using hemp plastics.
And then there are the extracts within the plant—cannabidiol (CBD) and others—the complexity of which we are only beginning to understand. Hemp is an amazing part of botanical medicine, and fortunately it can now be cultivated legally in the U.S. But it can be challenging for clinical practitioners to sort the helpful from the hype.
As someone who's worked in the industry for 30 years formulating natural products for animals, conducting research and talking to veterinarians about their experience, I'd like to lay out where things stand in the hemp and CBD industry, at least from my perspective.
Changes in the legal landscape
When the topic of CBD comes up, the first question most veterinarians have is whether anything major has changed on the regulatory front. And the answer? Not really. With COVID-19, the FDA has had more important things to focus on than whether pets are consuming CBD products.
But at the same time, consumer adoption of cannabis has been increasing rapidly. Our most recent slate of elections added a number of states where medical marijuana is legal, and when that happens, veterinarians in those states start thinking more about hemp—even though the laws governing hemp and medical marijuana are not connected in any way. Still, more veterinarians are using hemp and becoming comfortable with it.
We're also seeing a proliferation of companies producing and promoting hemp. Some are very good about researching and testing their products, and veterinarians increasingly know what to look for in terms of quality control. People in general are more comfortable using previously prohibited substances to help themselves and their animals feel better.
"[CBD is] not a politically polarized issue like many we're facing today. Conservatives see it as a libertarian issue. Liberals consider it a freedom from their perspective. It's a universal solvent, like water."
What's more, this increase in acceptance and usage of cannabis has been unaccompanied by bad things happening. We're not seeing animals dying. We're not seeing people committing crimes. We're just seeing a gradual, steady acceptance. Interestingly, it's not a politically polarized issue like many we're facing today. Conservatives see it as a libertarian issue. Liberals consider it a freedom from their perspective. It's a universal solvent, like water.
State of the science
With no federal funding, cannabis and CBD research has to be supported privately, usually by manufacturers. Several companies have funded studies with their products, and because they need a return on their investment, much of the research is directed toward showing how their own products work. But these studies also show what the products in general can do.
We now have several studies showing a benefit for CBD-dominant cannabis (another way of referring to hemp—see the terminology guide below) in dogs with osteoarthritis, and we've established dosage ranges that seem to be effective and safe.1-3 Another study analyzed nearly 30 veterinary products taken off the shelf to see if they actually contained what their label said they did and whether any heavy metals or other contaminants were present. The results were mostly positive.4 Veterinarians are increasingly aware that we have to be careful about product selection, ask for laboratory tests and look for a certain level of laboratory certification for those labs to be credible sources.
Quick terminology guide
Cannabinoid. Any of a number of closely related active compounds in the cannabis plant, including THC, CBD and others.
Cannabis sativa L. The scientific name for the cannabis plant, whether it contains high or low levels of THC. Referred to less formally as "cannabis."
Hemp. A version of the cannabis plant containing less than 0.3 percent THC. Often called "industrial hemp" since it is grown for a variety of purposes, including fabric and rope manufacturing.
Marijuana. A version of the cannabis plant containing more than 0.3 percent THC. (By the way, people in Canada people don't use the terms "hemp" and "marijuana" but rather "low-THC cannabis" and "high-THC cannabis," respectively.)
Researchers are also looking at different ways of administering hemp and CBD. For instance, the active ingredients in cannabis, CBD in particular, are generally poorly absorbed from the digestive tract because they're so fatty, or lipophilic. Researchers have found that if fatty supplements are taken with a meal, particularly a meal high in fats, absorption is better. That's what we're finding here. We're taking up CBD in a dropper, putting it directly in the pet's mouth or on a small amount of food, and following that up with a meal. We're finding that approach to increase absorption by four to six times—a substantial improvement!5 Other companies are doing work with liposomes, where the active ingredient is surrounded by a fatty shell, and they're finding that it's more rapidly absorbed.6
We also know that some animals respond better to a lower dose of CBD and some to a higher dose, but there's no way of predicting which patients will respond which way. Because the products can be expensive, I recommend starting with a lower dose than what might be considered optimal, give the pet's body a week or two to develop a steady state and escalate as needed. Studies show CBD is safe at higher levels for at least 12 weeks—the longest it's been studied so far at that higher dosage.7
Overall, there's been quite a bit of scientific progress to make veterinarians comfortable that evidence supports safe and effective use of these products. There's more coming, but these are the good things that have happened so far. It's a lot more than we had just a year ago.
More to discover
Cannabis became famous because of THC and its ability to get people high, and now CBD is being investigated, but there are hundreds of molecules in the plant whose benefits are waiting to be discovered. Many of them may do even more good than CBD.
For instance, some companies are starting to include cannabidiolic acid (CBDA)—the acidic or raw form of CBD—in their products, and it appears to be more bioavailable, better absorbed and 10 times more anti-inflammatory than CBD (although it appears that CBD works better at killing cancer cells).8 Other acidic cannabinoids include tetrahydrocannabinolic acid (THCA), cannabigerolic acid (CBGA) and cannabichromic acid (CBCA).
There are also the minor cannabinoids: cannabigerol (CBG), cannabichromene (CBC), tetrahydrocannabivarin (THCV), cannabidivarin (CBDV) and hundreds of others. Many may have potent effects, and we need to learn what those are. The terpenes are another class of compounds in the cannabis plant—aromatic oils that may have discernible effects. They're all being looked at.
We are truly in the infancy of our expansion of knowledge of the whole plant and which molecules have which benefits. Some people believe everything works optimally when taken together. But the future also involves targeted products, where the molecules are isolated or combined in certain ways to produce very specific results. The only thing holding us back is the time needed to do the research.
Misconceptions about cannabis
You don't need me to tell you there's a lot of noisy misinformation surrounding CBD and other elements of the cannabis plant. But I'll break down a few myths I hear quite often. One misconception promoted by those who advocate "full-spectrum" use of cannabis (consuming the whole plant, including THC) is that THC is necessary to activate CBD. Now, THC is a good component. It has a beneficial effect on the body when not at levels that produce intoxication. It can relieve pain, reduce inflammation, help with bowel problems and more. But you don't need THC in order for CBD and other cannabinoids and terpenes to work.
"... people say that CBD is not psychoactive. But CBD creates relaxation and reduces anxiety—which means it's psychoactive! But it's not intoxicating. It won't get you high."
Another misconception is that CBD sedates. It's actually the other ingredients in the cannabis plant that are sedating, such as cannabinol (CBN), a breakdown product of THC found in older plant material. Some terpenes, such as myrcene and linalool, can also be sedating, especially at higher doses. CBD in lower doses has actually been found to be mentally alerting.
On the other hand, I also hear people say that CBD is not psychoactive. But CBD creates relaxation and reduces anxiety—which means it's psychoactive! But it's not intoxicating. It won't get you high. That's the difference.
From wacky to wonderful
This plant, Cannabis sativa L.—it's amazing. There are cannabis-aholic-type people who almost worship it. Some people say it was brought to earth by aliens or that exposure to the plant precipitated our intellectual evolution. But the plant shouldn't be dismissed because of its bizarre reputation and history of illegality.
One reason I work actively in the hemp industry is to help uncover all of its hidden benefits. For example, hemp seed oil is rich in omega-3s, gamma linoleic acid and other anti-inflammatory fatty acids. The seeds are 20 to 30 percent protein—a form that is highly bioavailable. I'm involved in upcoming studies that I believe will be groundbreaking. There are worlds to be discovered within the cannabis plant, and I'm having more fun than I ever have in my career exploring them.
- Gamble L-J, Boesch JM, Frye CW et al. Pharmacokinetics, safety, and clinical efficacy of cannabidiol treatment in osteoarthritic dogs. Front Vet Sci 2018;5:165.
- Brioschi FA, Di Cesare F, Gioeni D et al. Oral transmucosal cannabidiol oil formulation as part of a multimodal analgesic regimen: effects on pain relief and quality of life improvement in dogs affected by spontaneous osteoarthritis. Animals 2020;10:1505.
- Kogan L, Hellyer P, Downing R. the use of cannabidiol-rich hemp oil extract to TREAT canine osteoarthritis-related pain: A pilot study. J Amer Vet Hol Assoc 2020;58:35-45.
- Wakslag JJ, Cital S, Eaton SJ et al. Cannabinoid, terpene, and heavy metal analysis of 29 over-the-counter commercial veterinary hemp supplements. Vet Med (Auckl) 2020;11:45-55.
- Boothe DM, Warner CG, Strunk R et al. The disposition of cannabidiol (CBD) in dogs after single dose oral administration. Poster presented at: ACVIM Forum on Demand (virtual); 2020 (in press).
- Verrico CD, Wesson S, Konduri V et al. A randomized, double-blind, placebo-controlled study of daily cannabidiol for the treatment of canine osteoarthritis. Pain 2020;161(9):2191-2202.
- Deabold KA, Schwark WS, Wolf L et al. Single-dose pharmacokinetics and preliminary safety assessment with use of CBD-rich hemp nutraceuticals in healthy dogs and cats. Animals 2019;9:832.
- Henry JG, Shoemaker G, Prieto JM et al. The effect of cannabidiol on canine neoplastic cell proliferation and mitogen-activated protein kinase activation during autophagy and apoptosis. Vet Comp Oncol 2020;e12669.