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Drs. Gary Richter and Trina Hazzah, co-founders of the Veterinary Cannabis Society (VCS), spoke on a panel at the American Holistic Veterinary Medical Association conference in Reno, NV, in October 2021. Below are excerpts from their question & answer session. 

Introduction: “The mission of the VCS,” Dr. Gary Richter explained in his introductory remarks, “is to educate veterinarians and pet parents about how to use cannabis safely and effectively. We work with regulators and legislators to sort out the myriad legal problems the veterinary profession currently has with cannabis. This is true for both hemp-based CBD products, but also for higher THC cannabis products if you happen to live in a state where that sort of thing is legal. The VCS is working with industry to make sure that the products that are being marketed and sold for animals are being done properly, they are manufactured safely, that product labeling and advertising is legal and appropriate. Finally, the VCS is working on product certification. So, for example, if you were to pick up a product that had the VCS seal on it you would know that that product has already been vetted for quality and efficacy.”

Question from the audience: What will set your rating system for products apart from what the NASC [National Animal Supplement Council] does?

Dr. Gary Richter: We’re actually consulting with a couple of people, including the NASC, to potentially collaborate when it comes to hemp-related products! So, really – NASC does an excellent job from the standpoint of evaluating products and their manufacturing practices and that sort of thing. The flip side of it, what we would bring to table, would be the educational aspect as well. So, we can provide veterinarians and the pet owner with what is out there from the standpoint of applications of certain ratios of cannabinoids, terpene profiles, what have you, so people are a little better able to pick the formula that most specifically serves whatever you’re treating.

Question: I was under the impression that you couldn’t give THC to dogs and cats because it’s toxic.

Dr. Trina Hazzah: When THC is dosed appropriately it can be exceedingly effective. As an oncologist, many of my patients that have cancer have been on very high doses of THC, sometimes 30 or more mg of THC two times a day. And that seems insane, right. If some people took that dose, they would be asleep for a week. But there is truly an art to getting veterinary patients up to those high doses. Not every pet can tolerate the same dose or titration schedule.  As we increase the dose over time, the CB1 receptors actually internalize, and tolerance occurs. So, you can actually get a patient up to larger amounts of THC when titrated with appropriate guidance. 

Question: Is cannabis effective for treating seizures in dogs and cats?

Dr. Hazzah: There is some evidence that THC can actually be fairly effective for seizures – mostly through the inhibition of the excitatory neurotransmitter glutamate, it can do so by binding to that CB1 receptor, which can inhibit the constant release of glutamate. But most of the research has been done on CBD-dominant products, or even CBD isolates being very effective for seizures. So oftentimes, if you’re going to have any THC, it would likely be a low amount in a seizure product. As we know, there is an entourage effect, which is really the description of the synergistic effect of all of the various cannabinoids, terpenes, and flavonoids found within the product. There are other cannabinoids and a few terpenes that have been shown to be help calm the nervous system and have anticonvulsant activity.

There is a randomized, blinded, controlled clinical trial that was published showing that epileptic dogs that received a CBD-dominant hemp-derived product had reduction in mean monthly seizures frequency compared to the placebo group.

Dr. Richter: Can you use cannabis as a stand-alone seizure control? For the most part that’s not been my experience. I will tell you that I have patients that are on pharmaceutical anti-epileptics and I have other patients that are just doing cannabis, herbs, acupuncture, etc. Obviously every seizure patient is their own unique special thing and how they respond.

Question: Can we talk about different cannabis ratios and cannabinoid acids? What are the differences in efficacy or usefulness between THC and THCA and CBD and CBDA?

Dr. Hazzah: Let’s start this discussion with some information about ratios and terminology. A CBD-dominant product means there’s more CBD than THC. And it’s typically going to be a high amount of CBD, when I say high, it’s usually 20 or 30:1, meaning 20 or 30 parts CBD to 1 part THC. And those types of products are usually used for seizures, for certain cancers, anxiety, mild to moderate inflammation/arthritis. CBD has over 65 targets, so it’s not just targeting the CB1, CB2 receptors like THC mostly does, it targets many other receptors. That’s why you’re seeing these hemp-derived products work so well and have been published to be efficacious for osteoarthritis and seizures in dogs. There are some thoughts that CBD-dominant products may be effective as an anti-diabetic because it can reduce blood sugar (it’s been shown in certain mouse models to do so).

A veterinary canine cancer cell culture study came out recently, looking at CBDA and CBD, and CBD had more antitumor effect on five different cancer cell lines in canines than did CBDA. But again, that’s in a petri dish and not in a patient. There are papers looking at THCA having anti-emetic, anticonvulsant and anti-inflammatory effects. It’s very unique in its anti-inflammatory effect as it inhibits TNF-alpha, which CBDA does not, while CBDA may provide anti-inflammatory effects partially through its non-selective COX inhibition. CBG (cannabigerol), seems to be the new fad cannabinoid. Some people call it the mother of all the cannabinoids. It’s really not. It’s mother, CBGA is the mother of all cannabinoids. CBG is a very special molecule in that it has profound anti-tumor effects. That’s where I think it’s going to do its magic. Also, CBG does has muscle relaxation effects. So for pets with muscle tension from pain or even urethritis, I can see how it may be an effective molecule.

Question: Can you talk about the bioavailability of the different forms, whether it is in some of the treats versus some of the drops or the extracts.

Dr. Richter: CBD is definitively bioavailable. There absolutely are some differences as far as how products are packaged. For example, I think it was one of the Colorado State studies that looked at naked CBD vs. a microencapsulated CBD vs. something that was applied topically. And it’s interesting because they got blood levels on all three of them. Ultimately, if I remember correctly, the microencapsulated one got to blood levels a little bit quicker. But it was also eliminated a little bit quicker than the naked CBD. The topical kind of got there, but it took longer. [One study] found that bioavailability was increased if given as a treat or if you didn’t give it with a treat, you gave it with a meal, compared to the ones that were given on empty stomach, where bioavailability wasn’t very good. And that’s been proven, they did it in monkey models, they did it in humans too, where they proved that there was increased bioavailability when you give any cannabinoid product along with a fatty meal. Most of the products you’ll find are in tincture form, so it’s not so difficult to put in a little peanut butter ball or something like that.

Question: What about sublingual products?

Dr. Richter: The problem with sublingual is just a practical issue in dogs or cats. When you’re talking about some cannabis product, you know either one of two things is going to happen when you put it under their tongue. Either they’re going to hate it or they’re going to love it and they’re going to want to swallow it. One way or the other it’s not staying there for long. I think it’s just a practical issue.

Comment from the audience: I’m finding topical CBD put on external wounds and cancer-type things, I am getting data from my clients with extreme results, even with mast cell tumors … This is using hemp-only topical products. I’ve got photos of a horse with a sarcoid tumor. I got people to donate topical and CBD oils. What it did was actually dried and healed, chunks at a time, this tumor just started to heal off the horse’s ear.


Dr. Richter: Very cool.

Question: Are there differences in treating cats and dogs with cannabis?

Dr. Richter: I think the one big difference cannabis-wise for cats versus dogs is, dogs will display a very specific type of THC intoxication, static ataxia – that is not something you will see in a cat. For unknown reasons, dogs have a really large number of CB1 receptors in their brain stem, more than people, more than cats.  Nonetheless, cats can still get THC intoxication, but it’s not going to present in quite the same way. But I’ve had a lot of luck with cannabis in cats. I think they do very well with it. I think if you get the right formula, so if you’re using a liquid, you only have to use one or two drops because it’s concentrated enough. I find that it works great and it’s very, very well tolerated.

More information about cannabis for animals and the Veterinary Cannabis Society can be found here.

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