The endocannabinoid system (ECS) has been evolving since the beginning of vertebrate species, but why did veterinary practitioners never learn about it in school? Just like our human counterparts’ veterinary practitioners have no or only a cursory understanding of the ECS and cannabis therapy. Veterinary practitioners have also been echoing that there “is no evidence” in animals. To the contrary, we have numerous studies utilizing cannabinoids and other cannabis molecules for therapeutic relief and translational studies that could be considered for any vertebrate creature. Here we review the current and pertinent literature in utilizing cannabis derivatives in animals and discuss the future forecast of cannabis in veterinary medicine.
Animal models of CBD utility for anxiety or panic attacks are supported by studies placing a prey species in front of a predator species and conditioned escape responses in mice and rats. According to these studies, anxiety or panic attacks would be related to the flight and freezing defensive responses elicited by threats which expression was decreased in both models (14). Canopy Growth has announced the completion of their anxiety study in companion animals that are currently awaiting publication. The author is aware of other anxiety-related research being conducted in cats and birds with hopeful publication in the next year.
Besides the alleviation of disease processes, veterinary scientists are exploring hemp for its anxiety-reducing effects and nutritional content increases in production animals. Stress on food-producing animals is directly correlated to poorer production of eggs, milk, down, wool, or muscle growth for meat producing animals. By exploring the use of naturally occurring cannabinoids in biomass from hemp production for other uses, we are beginning to see the utility for this welfare and economic challenge. The nutritional content of cannabis biomass is also being studied as feed for production animals, since seeds are particularly full of beneficial fatty acids (15–18).
Aside from pharmacokinetic, pain, seizure, and anxiety studies, we have seen scientific articles looking at cannabinoid receptor proliferation in feline and canine epidermal tissues suggesting the efficacy of topical and systemic applications for atopic dermatitis in dogs and hypersensitivity dermatitis in cats (19,20).
Other studies looking at ECS distribution in various tissues are those interested in gastrointestinal function. One study published by Glaiazzo and colleagues looked at CB1, CB2, GPR55, and PPARa in canine gastrointestinal tissue, giving us deeper insight to the anatomical basis of supporting therapeutic cannabis in relieving motility disorders and visceral hypersensitivity in canine acute or chronic enteropathies (21). We have also seen studies looking at protective effects, specifically for gastrointestinal mucosal lesions secondary to acute pancreatitis in rat models. This is of particular interest in companion animals because pancreatitis is a common occurrence (22).
Anticancer effects are one of the more common interests with owners. The scientific literature (in rodent models) is promising in several different cancer types, and certainly for the alleviation of symptoms related to chemotherapy or radiation therapy (23,24). A canine cancer study at the University of Florida has some exciting preliminary in-vitro results for three different types of canine cancer cells. Hopefully, we will see similar results in the on-going in-vivo study.
While the legal status of cannabis products continues to play out, it is critical that we continue to push for quality scientific data to support therapeutic evidence. Just like in human medical cannabis circles, the veterinary side of things will continue to evolve, looking for specific cannabinoid and terpene profiles for various ailments or ECS support. As scientists, consumers, and animal lovers, we must pressure cannabis manufacturers to produce products following good manufacturing guidelines, use safe ingredients for animals, and be transparent with what is in their products. To that end, manufacturers should suggest dosing regiments based on science instead of anecdotes. We must also pressure local governments, mainly state veterinary and pharmacy boards, to adopt legislative language to allow veterinary professionals to discuss, recommend, and, in some cases, prescribe cannabis product for our pets. Lastly, we must encourage the veterinary profession to educate themselves on this topic.
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Stephen Cital, RVT, SRA, RLAT, VCC, VTS-LAM (Res. Anesthesia) is the co-founder of the Veterinary Cannabis Academy and consultant and research librarian for Veterinary Cannabis Education and Consulting in Wheat Ridge, Colorado. Direct correspondence to: [email protected]
How to Cite This Article
S Cital, Cannabis Science and Technology 2(2), 56-60 (2019).