Deep Dive: Cannabis in Veterinary Medicine
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Cannabis in Veterinary Medicine
A 2019 chapter entitled "Cannabis in Veterinary Medicine: Cannabinoid Therapies for Animals" that was published in the book Nutraceuticals in Veterinary Medicine investigated the use of cannabis or animals species, describing it as "an area of growing interest, largely due to the therapeutic benefits being observed for humans and animals in the era of cannabis legalization."
The chapter explored "the literature available on cannabis, its interactions with the endocannabinoid system, and how animal species interact with various formulations and cannabis treatments." It noted that cannabis preparations have been used in the treatment of animals since the 1800s, "when cannabis had become a popular herbal remedy at a time prior to the development of the pharmaceutical industry."
Reported the scientists: "A thorough review of the scientific literature has been compiled here for veterinarians and veterinary scientists to better understand this fascinating and emerging [cannabis] therapy and, by understanding it, to be better able to deploy cannabinoid therapies for their patients and formulate more effective cannabinoid medications."
"For our companion animal species [like] dogs, cats, and horses, the use of cannabis products did not gain popularity until the state-by-state legalization of cannabis for medicinal purposes began in the mid-1990s."
"For our companion animal species [like] dogs, cats, and horses, the use of cannabis products did not gain popularity until the state-by-state legalization of cannabis for medicinal purposes began in the mid-1990s," explained the authors. "Pet owners, learning of the many benefits that cannabis has created for people, naturally began to explore its use in their pets for the medical problems that were not easily solved by conventional veterinary medicine," reported the chapter.
Animals Problems Addressed
Cannabis in Veterinary Medicine. These problems include types of epilepsy that are resistant to pharmaceutical treatment, "pain that is poorly responsive to opiates, steroids, and nonsteroidal anti-inflammatory drugs," osteoarthritic pain, and several side effects of cancer treatment, including nausea and vomiting and perhaps treatment of the cancer itself (including reductions in tumor size).
The five authors of the chapter explained that the endocannabinoid system (ECS) "has been identified in nearly all animals, from complex mammals like primates to phylogenetically primitive animals such as the cnidarians [invertebrates that includes jellyfish, hydras, sea anemones, and corals]." They noted that the "universal presence and early emergence" of the ECS "is a strong indicator of its biological importance."
The endocannabinoid system (ECS) "has been identified in nearly all animals, from complex mammals like primates to phylogenetically primitive animals such as the cnidarians."
The chapter noted that cannabinoid receptors like CB1, CB2, GPR18, GPR55, and others are expressed in most animals, including "vertebrates (mammals, birds, reptiles, and fish) and invertebrates (sea urchins, leeches, mussels, nematodes, and others)."
The most primitive animal to feature an ECS is the Hydra (H. vulgaris), "a cnidarian in the class Hydrozoa, which [was] the first animal to develop a neural network." But what is the role of the ECS in such a crude creature? "The major function of the ECS in the Hydra is to control the feeding response."
Cannabinoid receptors like CB1, CB2, GPR18, GPR55, and others are expressed in most animals, including "vertebrates (mammals, birds, reptiles, and fish) and invertebrates (sea urchins, leeches, mussels, nematodes, and others).
Despite the fact that many animals share ECS features such as CB and other types of cellular receptors, significant differences were noted by the scientists. "It was found that the binding affinities for canine CB2 receptor were 30 times less than those measured for human and rat CB2 receptors," reported the scientists. They also noted that the functional properties of the CB2 receptor vary depending on a number of factors.
The chapter noted that previous studies identified CB1 receptors in several parts of the anatomy of a dog, including "in salivary glands, hair follicles, skin, and hippocampus [an area of the brain]."
ECS In All Veterinary Species
Cannabis in Veterinary Medicine. "It is evident from this data that all veterinary species contain an ECS," declared the scientists, who added that an understanding of how the ECS operates in these animals "is critical to the development of clinical applications for endocannabinoids and the phytocannabinoids derived primarily from Cannabis sativa L."
One of the problems in the use of cannabinoids from cannabis in the treatment of veterinary animals has been a lack of clinical trials to determine mechanisms of efficacy and safety profiles that would allow veterinarians and other professionals to better leverage cannabis in treatment therapies. "A thorough review of the literature reveals no published clinical trials prior to the studies reported in this chapter involving phytocannabinoids in dogs, cats, or horses," reported the scientists.
Benefits include "the reduction of anxiety; relief of pain; improvement of mobility in animals with osteoarthritis; reduction in tumor size; improved control of type 2 diabetes; and improved control of epileptic seizures."
Cannabinoid Benefits Defined
Cannabis in Veterinary Medicine. The chapter reported a wide range of potential positive outcomes gained from the medical treatment of veterinary animals with cannabis. Observed benefits include "the reduction of anxiety; relief of pain; improvement of mobility in animals with osteoarthritis; reduction in tumor size; improved appetite; improved control of type 2 diabetes, inflammatory conditions, and digestive issues; and improved control of epileptic seizures."
"Of the 113 cannabinoids identified in [cannabis], the majority can be cataloged as analogs of Δ9-tetrahydrocannabinol (Δ9-THC), CBD, cannabichromene (CBC), cannabigerol (CBG), cannabinol (CBN), cannabicyclol (CBL), cannabielsoin (CBE), and cannabitriol (CBT)," noted the chapter's authors.
The chapter explained cannabinoid acidic precursors and how they produce the neutral versions of cannabinoids, such as CBD and THC, with which most cannabis consumers and industry professionals are familiar. "Though THC and CBD are the most well-known cannabinoids, it is important to note that they are not synthesized in the cannabis flower directly. Rather, they are synthesized in their acidic forms in the plant," noted the chapter.
It explained how these acidic precursors undergo a process called decarboxylation in which they convert to their neutral isomers. "The application of increased heat speeds up the reaction in which a CO2 molecule is released from THCA to form THC in a process termed decarboxylation," wrote the scientists.
"Though some people refer to this reaction as 'activating' the cannabinoids, it is a bit of a misnomer, as the acidic versions of these compounds also have been shown to induce medical benefits themselves, most notably anti-inflammation properties."
They emphasized that potential benefits conveyed by the acidic precursors are as significant as those of their neutral siblings. "Though some people refer to this reaction as 'activating' the cannabinoids, it is a bit of a misnomer, as the acidic versions of these compounds also have been shown to induce medical benefits themselves, most notably anti-inflammation properties," they wrote.
Cannabimimetics
Cannabis in Veterinary Medicine. Nearly a century of cannabis prohibition—and the underground culture that it has produced—has resulted in a number of misunderstandings and much misinformation about cannabis. Some claim that cannabinoids are produced by non-cannabis plants.
However, this is not true. What is true is that a number of cannabinoid-like molecules (that are not, strictly speaking, cannabinoids—including terpenes) bind or otherwise interact with ECS receptors. "These compounds are classified as cannabimimetics or cannabinoid-mimicking compounds. Some of the plants that produce cannabimimetics are widely used in herbal medicine and some are even part of our regular diet," reported the scientists.
The chapter reported that an endocannabinoid produced by the human ECS, anandamide, is also made by black truffles. In addition, it noted that echinacea roots "produce endocannabinoid-like molecules that have been shown to bind to cannabinoid receptors in rodents." It also reported that the herb kava kava (Piper methysticum) "contains yangonin, a kavalactone that displays significant binding affinity for CB1 [receptors]."
Biphasic Response Curves
Cannabis in Veterinary Medicine. The chapter reported that veterinarians who have recommended phytocannabinoids such as CBD and THC to their patients have witnessed a biphasic response curve in the animals that is similar to responses to these phytomolecules by humans.
They reported that the "nearly universal distribution of the ECS in all chordates, and in many invertebrates" means that the benefits delivered by cannabinoids to humans "also can be applied to most veterinary species."
"'Biphasic' means that a low dose (or 'microdose') will generate one set of effects and address one set of clinical issues and a high dose (or 'macrodose') will produce a second set of effects and address a second set of clinical issues," explained the authors. In humans, THC exhibits a biphasic response by reducing anxiety at low doses, but has shown to increase anxiety and even produce panic attacks at strong doses (especially in novice consumers).
Cannabis in Veterinary Medicine: Conclusions
Cannabis in Veterinary Medicine. The chapter concluded that the volume of "objective, non-biased scientific evidence" for the use of medical cannabis by veterinary animals is smaller than that for humans. "Nonetheless, there are now several university-based, prospective, double-blinded, placebo-controlled, randomized clinical studies examining CBD from hemp extracts to measure its safety and pharmacokinetics," reported the authors, who said two areas of focus are "veterinary conditions such as osteoarthritis and epilepsy."
They reported that the "nearly universal distribution of the endocannabinoid system in all chordates, and in many invertebrates" means that the benefits delivered by cannabinoids to humans "also can be applied to most veterinary species."
View the original study.
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