For both people and animals, medicine tends to trend high-tech. One of the most promising new veterinary drug therapies, however, incorporates ingredients derived from cannabis, a plant that’s been in use by humans for thousands of years. This primer covers the basics of veterinary cannabidiol (CBD) and reflects what’s currently known.
New findings are released every day, it seems, so if you’re interested, we advise staying on top of developments by bookmarking a few reliable websites. If your vet is open to discussing it—for legal and licensing reasons, not all are—we strongly advise starting there.
What is CBD?
Cannabidiol (CBD) is one of at least 60 known plant-based cannabinoids, naturally occurring active chemical compounds that act on the brain and body. It’s derived from cannabis, a complex plant in the Cannabaceae family, and has no psychoactive effects —it provides “the benefits without the buzz,” as one writer put it.
CBD is the plant’s second most abundant cannabinoid; first place goes to THC, or tetrahydrocannabinol, which generates marijuana’s distinctive high. It’s extracted and processed as either an isolate (on its own) or as a full-spectrum oil, one of a group of related cannabinoids that often includes cannabigerol (CBG), cannabichromene (CBC), cannabidivarin (CBDV), tetrahydrocannabivarin (THCV), terpenes and flavonoids.
Over millennia, humans have domesticated, developed and cultivated multiple strains of cannabis and used them for a variety of purposes. Today, generally speaking, the two you’ll hear the most about are hemp, which is legally defined as cannabis plants that contain less than 0.3% of the psychoactive THC, and marijuana (strictly speaking, a product rather than a plant type), which has more than 0.3% THC. Many CBD products for dogs are sourced from hemp.
Every animal with a spinal column has an endocannabinoid system (ECS), which scientists estimate evolved more than 600 million years ago and has been carried forward across the millennia. This ancient system—discovered through the work of several researchers between roughly 1965 and 1995—is named for Cannabis sativa L., the plant species that most dramatically affects it. Its basic functions have been summarized as to “relax, eat, sleep, forget and protect.”
To do this, the ECS maintains the body’s internal balance through a network of activators and receptors that most notably affect the central nervous system and the immune system. Cannabinoids are the ECS’s messengers, and their effects depend on the receptors to which they bind.
This is a very specific process; a receptor will only accept the particular compound for which it exists, and is unaffected by others. Research shows that cannabinoid receptors are similar across species, functioning much the same way in dogs as they do in people, although dogs have far more receptors in their brains than any other animal tested (including humans).
Robert J. Silver, DVM and veterinary herbalist of Boulder, Colo., suggested another way to understand this system: “Receptors are like locks, and cannabinoids are like keys. They fit together perfectly. Once the cannabinoid connects to the receptor and turns that lock, a series of actions occur in the cell membrane; these actions are responsible for some of the cannabinoid’s effects.”
Whole-plant or full-spectrum extracts are considered to be the most therapeutically effective. In this form, CBD works in conjunction with other cannabinoids to produce what’s called the entourage effect: the result of numerous types of cannabinoids, each with a specific function, working together. You’ll sometimes see THC in the mix as well; aside from its recreational aspects, it has its own set of medicinal properties and can be particularly effective against severe pain.
Is CBD safe? Does it work? How does it work?
These are just a few of the questions that can only be reliably answered by evidence-based scientific research, which is now taking place in the U.S. and around the world, and is the best way to separate fact from fiction.
More work has been done to discover CBD’s effects on people than on animals—for example, at least 132 original studies have focused on CBD’s human-safety profile—but that tide seems to be turning. Take, for example, the following:
• In 2016, Dr. Stephanie McGrath, neurologist and assistant professor at Colorado State University’s College of Veterinary Medicine & Biomedical Sciences, completed a preliminary pharmacokinetic (what happens to a drug in the body) and safety study on CBD. Following this study, Dr. McGrath began two pilot studies involving owner-enrolled dogs with poorly controlled epilepsy and painful osteoarthritis. These have now ended and results on the epilepsy study are scheduled for publication in the Canadian Veterinary Journal later this year. One of its big-picture findings: 89 percent of dogs who received CBD had a reduction in the frequency of seizures. (McGrath and her team are now starting work on a larger epilepsy-focused project.)
• The results of a study led by Dr. Joe Wakshlag, associate professor and section chief of nutrition at Cornell, currently under review for publication, also contribute to the knowledge bank. According to the abstract, its objectives were to “determine the basic oral pharmacokinetics, determine safety and assess efficacy of CBD oil in managing pain in dogs with osteoarthritis.” The Canine Brief Pain Inventory and Hudson activity scores reportedly showed a clinically significant reduction in pain and an increase in activity with CBD treatment.
• Dr. Dawn Boothe, director of clinical pharmacology at Auburn University College of Veterinary Medicine, is studying CBD as a treatment for epilepsy in dogs and is also developing an assay to measure cannabinoid toxicity and efficacy.
• Dr. Jamie Peyton, chief of small animal integrative medicine at University of California, Davis, Veterinary Medical Teaching Hospital, led a late 2017/early 2018 study on the current use of cannabis with companion animals. By anonymously filling out an online questionnaire, participants provided the study with data that can be used to inform future research (the study is now closed).
A Research Roadblock
CBD could prove to be a life-improving medication for dogs, but without the backing of clinical research to establish its effectiveness and dosing, it’s hard to know for sure. That research is hindered by cannabis’s federal Schedule 1 drug classification, which puts traditional academic research institutions in a legally ambiguous position. It also makes funding harder to come by; much of the work currently underway is sponsored by companies who produce CBD products.
In the future, we’ll look into questions of CBD and the law, delve into the role veterinarians can play in your decisions and provide a glossary of terms to help guide you through this evolving landscape. For now, check out The Bark’s informative CBD & Dogs section.