The actual use of Cannabis in pain treatment for dogs and cats and future prospective
The use of cannabinoids in veterinary medicine is controversial for ethical and legal reasons. The approval of drugs from the competent authorities, and their use, are complicated by the application of laws and professional regulations of each country. Hemp-derived compounds are gaining medical approval for their benefits, and their use is an emerging field of interest with still limited studies available; further research is needed to document and support their clinical use. Cannabinoids are a group of compounds that interact with the endocannabinoid receptor system, extracted from hemp (Cannabis sativa L.), that have been tested for different therapeutic purposes in dogs, cats, and ferrets; these compounds include antispastics, antiemetics, anticonvulsants, and appetite stimulants known for their neuroprotective, analgesic and anti-inflammatory properties. The endocannabinoid receptor system, composed of two cannabinoid receptors (CB1 and CB2) and their ligands, plays a key role in pain modulation and inflammation attenuation. Cannabidiol (CBD) is a non-psychotropic cannabinoid that exerts immunomodulatory, antihyperalgesic, antinociceptive and anti-inflammatory effects, acting as a non-competitive allosteric antagonist of CB receptors.
Based on the published studies on the endocannabinoid system, its ligands, receptors, mechanism of action and signalling has led to research showing the therapeutic applications of CBD in dogs. The main applications ported include osteoarthritis-associated pain, aggressive behavior, and epilepsy. In dogs with idiopathic epilepsy, CBD appears to alleviate seizure frequency. A study by Brioschi et al., showed that CBD relieved osteoarthritic (OA) pain and improved life quality in dogs, allowing a reduction of other drugs’ dosage and thus minimizing their potential side effects. The main route of administration of CBD in animals is oral; several bioavailability studies reported how CBD availability when administered orally is very low, with an average value of 10%, presumably due to a high first-pass effect through the liver, where it also gives its major adverse effects. The CBD has been tested in different human, animal and in vitro models in order to determine its efficacy in pain modulation based on the interaction with CB1 and CB2 receptors.
As cited above, CBD has been studied to control pain in companion animals in chronic pain models, mainly related to OA. Studies reported the presence of CB receptors in the synovial fluid and adjacent inflamed tissues; this aspect is why cannabinoids can be effective in osteoarthritis pain treatments for dogs. Different studies have been conducted to test CBD efficacy in osteoarthritis pain modulation, evaluating signs of pain with different scoring systems, however, different CBD formulations and compositions do not permit researchers to define the effective doses comparing the studies. Cannabinoids are suggested as a complementary and effective alternative to traditional analgesics in osteoarthritis therapy. The result reported in OA studies suggests that similar results can be obtained in other diseases where CB receptors are present and their modulation can have an impact on the pain treatment. Considering that companion animals, due to high quality food and the augmented medicinal availability in recent years, are living longer than 20 years ago, the need for treatments for chronic pain-related diseases will increase in the coming decades.
In conclusion, the future of chronic pain treatment, based on studies already reporting positive results for osteoarthritis pain in companion animals, can look at Cannabinoids as a good solution for an alternative/complementary therapy to those currently used. In order to reach the objective of having effective “Cannabis-based” drugs on the market, the involvement of pharmaceutical industries is the next step, permitting Cannabis to pass from an academic application to the clinical application and to have a future in the marketing of registered Veterinary Medicinal Products.
Bibliography
Brioschi 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
Gamble et. al: Pharmacokinetics, Safety, and Clinical Efficacy of Cannabidiol Treatment in Osteoarthritic Dogs. Frontiers in Veterinary Science 2018, 5, 165.
Cortés et. al.: The role of cannabinoids in pain modulation in companion animals. Frontiers in Veterinary Science 2023.
Polidoro et. al.: Pharmacokinetics of Cannabidiol Following Intranasal, Intrarectal, andOral Administration in Healthy Dogs. Frontiers in Veterinary Science 2022.
Verrico et. al.: A randomized, double-blind, placebo-controlled study of daily cannabidiol for the treatment of canine osteoarthritis pain. Pain, 161 (2020) 2191–2202.
