Cannabis provides a promising new pharmacotherapy for many different diseases in canine and feline patients.
Hemp is cannabis containing 0.3% tetrahhydrocannabinol or less by dry weight, and is legal in most US states. The resin glands (trichomes) of cannabis plants produce around 100 phytocannabinoids that interact with our body’s receptors to produce many different beneficial effects, such as analgesic, anti-inflammatory, anti-obesity, anti-neoplastic, anxiolytic, neuroprotective, and anticonvulsant effects. The most-studied phytocannabinoids include Δ9– tetrahydrocannabinol (Δ9-THC), cannabidiol (CBD), cannabigerol (CBG), cannabidivarin (CBDV), and cannabichromene (CBC).
Endocannabinoids (endogenous cannabinoids, or EC) are bioactive lipid mediators made by the body. The two main EC, anandamide (AEA) and 2-arachidonoylglyerol (2-AG), are released on demand and act through cannabinoid CB1 and CB2 receptors located throughout the body. Endocannabinoids can bind to either receptor; e.g. an EC might bind to a CB1 receptor in a spinal nerve to relieve pain, or to a CB2 receptor in a white blood cell to signal that inflammation is present.
The endocannabinoid system (ECS) is a complex cell-signaling system comprised of endocannabinoids, receptors, and enzymes. Its primary role is believed to be homeostasis of many biologic functions, including: inflammation; chronic pain; metabolism; appetite; sleep; stress; learning and memory; motor control; mood; and cardiovascular, bone, muscle, and liver health. While THC and CBD can both bind to CB1 and CB2 receptors, they do so in different ways; in fact, CBD can influence receptors via non-binding mechanisms. CBD/receptor interactions prevent endocannabinoids from being broken down, enhancing their effect. CBD can help with common issues (e.g. pain, inflammation, and nausea) shared by many different conditions. A patented Liquid Structure™ technology hemp isolate used in an Atlantic Bottlenose dolphin with bilateral perforated corneas improved ocular discomfort and inflammation as shown through reduction in tramadol administration and daily blepharospasm1. CBD also has promising potential as an effective therapeutic agent in alleviating obesity, insulin resistance and diabetes mellitus.
It is theorized that clinical endocannabinoid deficiency (CECD) exists: humans (and perhaps dogs and cats) have an underlying endocannabinoid “tone” resulting from the various levels of EC, receptors, and enzymes present; this tone may be deficient in some individuals, resulting in hyperalgesia and central sensitization. Examples of human conditions in which CECD may play a role include migraines, fibromyalgia, and irritable bowel syndrome.
Excessive chronic oxidative stress leads to faster aging and plays a negative role in disease expression, including diabetes mellitus, arthritis, cataract formation, immune-mediated diseases, and neoplasia. Our bodies contain innate antioxidants that are depleted through normal aging, and are more rapidly depleted by diets poor in important nutrients, obesity, excessive stress, and exposure to excessive radiation. The intake of exogenous antioxidants that support a variety of oxidative stress pathways helps replenish depleted antioxidants and rebalance the body’s cellular redox systems.
CBD has been shown to have several direct antioxidant effects. CBD prevents superoxide radical formation, reduces nitric oxide levels, reduces reactive oxygen species (ROS), and modifies the redox balance by changing the level and activity of antioxidants. The most important antioxidant activity of CBD, like endocannabinoids, is associated with the fact that CBD (depending on the concentration) can activate, antagonize or inhibit cannabinoid receptors.
A recent study in dogs with induced anterior uveitis found that CBD may be an option when corticosteroids or NSAIDS are contraindicated, or as a long-term anti-inflammatory treatment option for dogs with chronic uveitis.2 This study also found that, unlike in humans and laboratory mice, CBD does not appear to increase intraocular pressure in dogs. More studies are underway investigating CBD’s anti-inflammatory effect on uveitis in companion animals.
The addition of exogenous CBD may enhance ECS function and provides a promising new pharmacotherapy for many different canine and feline diseases.
1 Mejia-Fava J, Vargo MG, Colitz CMH, Schwartz JR, Rosenfeld MJ. An Ocular Case Study of an Atlantic Bottlenose Dolphin (Tursiops truncatus) Using a Medical Regimen of Various Topical, Oral, and Alternative Modalities Including Crystalline Hemp Extract. Poster presented at: The International Association of Aquatic Animal Medicine annual conference; May 25, 2021; Tampa, FL.
2 MdL Henriksen,1 HM Terhaar,1 E Davey,1 H Patterson,1 S McGrath,1 A Hess,2 MR Lappin,1. Clinical findings in dogs treated with oral cannabidiol (CBD) versus prednisolone acetate 1% ophthalmic suspension for experimentally induced uveitis. Submitted to the Annual Conference of the American College of Veterinary Ophthalmologists 2021.