Cannabis e anestesiologia veterinária: uma revisão bibliográfica

Abstract

Cannabis sativa L., popularly known as marijuana, produces more than 500 compounds, including phytocannabinoids, flavonoids, terpenes and fatty acids. The medicinal use of cannabis was recognized in 2,700 BC in various cultures. Its first uses included analgesic, anticonvulsant, anti-inflammatory and antibiotic effects. Its prohibition, however, despite evidence of its benefits, has made research challenging due to bureaucracy and legal issues. Cannabinoids are classified as phytocannabinoids, endocannabinoids and synthetic cannabinoids. The most widely researched phytocannabinoids are CBD, a minimally psychoactive molecule with therapeutic effects, and THC, which has psychoactive effects. Studies in the 1980s led to the discovery of the endocannabinoid system (ECS). This system integrates cannabinoid receptors, their ligands and enzymes, and has since been the subject of research for demonstrating an important role in homeostasis due to the wide distribution of its receptors throughout the body. CB1 and CB2 receptors are expressed mainly in the central nervous system and the immune system, respectively. Endocannabinoids, such as 2-AG and AEA, are lipophilic molecules that bind to these receptors, regulating various physiological functions. The use of cannabis in animals has a long history, however veterinary research is limited due to legal restrictions. Cannabis is most commonly used to treat the pain of osteoarthritis and as an anticonvulsant in epilepsy. In addition, studies suggest that cannabis may be useful as an anti-tumor agent, anxiolytic, anti-inflammatory and anti-emetic. Cannabinoids, used to complement conventional painkillers, are effective in treating acute, chronic and neuropathic pain. They act on the nociceptive pathway, in a multimodal approach, and are advantageous for acting on both the perception and modulation of pain. There are still few studies relating cannabis in a context aimed at veterinary anesthesiologists. However, it is known that the endocannabinoid system and drugs used in routine anesthesia share mechanisms of action. It is known that the use of cannabis as a pre-anesthetic medication for dogs reduces the requirement for propofol and the time needed to reach the anesthetic plane. Owners have shown increasing interest in exploring the therapeutic use of cannabis products for their pets. The American Society for the Prevention of Cruelty to Animals (ASPCA) has recorded an increase in the inadvertent exposure of small animals to cannabis, mainly through the consumption of THC-containing foods such as brownies and cookies. The reason for this increase is still unclear, and the solution to intoxication is supportive treatment. Given the great potential of cannabis in medicine and the challenges posed by the lack of studies, the aim of this review is to demonstrate the potential uses and benefits of cannabis in veterinary medicine and to encourage interest in research involving the plant's components and veterinary anesthesiology.