CBD for Osteoarthritis in Horses

While many horse owners have enthusiastically jumped aboard the CBD bandwagon, research supporting the rampant use of commercial products remains scarce. To investigate the use of CBD for osteoarthritis (OA), researchers recently discovered that cannabinoid receptors exist in healthy and arthritic joints of horses.

Osteoarthritis is the most pervasive disease of the equine musculoskeletal system. This degenerative disease affects the entire “joint organ,” which includes the articular cartilage, subchondral bone positioned under the cartilage, joint lining—called the synovium or synovial membrane—as well as the joint capsule and other structures.

“There is no known cure for OA at this time, leaving owners and veterinarians managing  joint discomfort with anti-inflammatory drugs and corticosteroids, both of which are associated with possible significant side effects. In lieu of those medications, horses may benefit from oral joint health supplements containing glucosamine, chondroitin sulfate, and hyaluronic acid, such as those offered by Kentucky Equine Research. Studies have shown that these ingredients help decrease inflammation through multiple pathways and may provide molecular precursors to cartilage cells to support building new, healthy cartilage in arthritic joints,” advised Katie Young, Ph.D., a nutritionist for Kentucky Equine Research.

Cannabis is not a single compound but is instead composed of over 400 distinct molecules (cannabinoids), including cannabidiol which is perhaps better known as its common name, CBD. CBD and related chemicals are believed to bind to specific protein receptors, such as cannabinoid type 1 and 2 (CB1 and CB2, respectively) found on or in various cells throughout the body. Exogenously administered cannabinoids such as CBD are believed to stimulate CB1 and CB2 receptors. When those receptors are located in the nervous system, activation of the nerve CB receptors purportedly induces an analgesic effect.

“Mirroring patterns in human practices, CBD is increasingly proposed as a pain-relieving supplement for horses with osteoarthritis. But it was only recently, in the study by Miagnoff and colleagues^* , that CB receptors were identified in both healthy and arthritic metacarpophalangeal, or fetlock, joints of horses,” shared Young.

In that study, 25 fetlock (ankle) joints obtained from a tissue bank were dissected. The degree of inflammation and amount of cartilage damage were characterized. Synovial membrane samples were also collected and analyzed microscopically to determine the presence or absence of CB1 and CB2 receptors.

Both CB1 and CB2 receptors were identified in synovial membrane cells, called synoviocytes, as well as blood vessels located within synovial tissues. Receptors were found in both healthy and inflamed joints secondary to naturally occurring osteoarthritis. Further, expression of both CB receptors increased with an increasing degree of inflammation.

“There is a significant need for safe, effective methods of pain control and disease-modifying drugs to address osteoarthritis in horses. Research in humans and other animals suggests that the endocannabinoid system may be a promising target for this purpose. Finding CB1 and CB2 receptors in inflamed equine joints with evidence of osteoarthritis supports additional studies on CBD in horses for managing equine osteoarthritis. Finding these receptors also suggests that cannabinoid compounds may have a favorable effect on joint inflammation and pain. Additional studies including larger numbers of subjects as well as clarification of mechanisms of action are warranted,” summarized Young.

When choosing oral joint health supplements to support horses suffering from osteoarthritis, be certain to only pick quality nutritional supplements, as not all products are manufactured in accordance with good manufacturing practices. As a result, contaminated products that do not contain the type or amount of ingredient that is listed on the label abound leave arthritic horses untreated.

 ^*Miagkoff, L., C.A. Girard, G. St.-Jean, H. Richard, G. Beauchamp, and S. Laverty. 2022. Cannabinoid receptors are expressed in equine synovium and upregulated with synovitis. Equine Veterinary Journal:13860.