CBD Improves Pain, Quality of Life for Arthritic Horses, Study Says

With an eye on understanding better ways to provide horses alleviation from chronic, debilitating osteoarthritis pain, researchers at the University of Messina in Italy found that transmucosal cannabidiol (CBD) provides pain relief and improves the quality of life with no side effects.^*

Osteoarthritis is a common cause of musculoskeletal disease in horses, often leading to reduced welfare. In addition to overt pain, signs of severe osteoarthritis include a reluctance to move and be handled for everyday care, such as lifting hooves for cleaning or farriery care.

“Osteoarthritis has no cure and is a slowly progressive, degenerative condition. Current management strategies include nonsteroidal anti-inflammatory drugs (NSAIDs), oral joint health supplements such as Synovate HA, as well as regenerative therapies,” said Kathleen Crandell, Ph.D., a nutritionist for Kentucky Equine Research.

Even when a multimodal treatment approach is used, many horses do not achieve relief from chronic pain. Further, long-term NSAID use, as with phenylbutazone or bute, is associated with adverse effects such as gastric ulcers and kidney disease.

CBD is becoming increasingly popular in both human and veterinary medicine partly because it is perceived as a natural treatment and because a growing body of data supports its pain-relieving and anti-inflammatory effects.

To determine if CBD helps relieve pain due to osteoarthritis, 24 client-owned horses residing on a single equine operation, a riding club, were recruited. All horses were considered healthy except for having mild lameness attributed to osteoarthritis in one or more fetlock joints.

Horses were randomly assigned to receive either a placebo or 15% CBD emulsified in hemp oil administered orally (0.03 mg/kg) once daily for 14 days. All horses included in the study were also administered phenylbutazone (2.2. mg/kg intravenously) once daily for five days. Horses were then evaluated daily for the 14-day study period. Measures included heart and respiratory rates, and pain was quantified using the Horse Chronic Pain Scale.

“This pain scale asks 15 questions that assess various aspects of equine behavior. A total pain scale from 0 or no pain to a maximum pain score of 45 is assigned based on these questions,” Crandell explained. Three independent observers, all known to the horses, assessed every horse each day.

This study found that when CBD was combined with phenylbutazone:

• Horses had significantly reduced heart rates from day 9 through day 14 of the study compared to baseline values at the start of the study;
• Significantly lower heart rates in the CBD group compared to the placebo group on days 12, 13, and 14;
• Respiratory rates were significantly decreased in the CBD group on days 5, 7, and 9 through 15 compared to baseline; and
• Total pain scores determined using the Horse Chronic Pain Scale decreased significantly in both the placebo and CBD groups, but the scores were significantly lower in the CBD group compared to the placebo on days 9 through 14.

Importantly, no adverse effects were appreciated in any horse during the study period. Horses were observed for signs of sneezing, headshaking, licking, nausea, excess salivation, sedation, lethargy, incoordination, urinary incontinence, and diarrhea, among others.

“The researchers concluded that the addition of CBD to an established analgesia protocol of phenylbutazone lowered heart and respiratory rates and pain scores, which could translate to an improved quality of life,” Crandell said. “Having an adjunct product for osteoarthritis may reduce or even potentially eliminate the need for long-term NSAIDs, thereby limiting the risk of adverse effects associated with those medications.”

The exact mechanisms by which CBD decreases pain remain unknown and require further study.

“While this study only considered the effect of CBD combined with phenylbutazone, a reasonable next step would be to determine the effect of adding high-quality oral joint support supplements on osteoarthritis-associated pain,” Crandell noted.

Horses involved in sport should be given CBD with the knowledge that it might be considered a controlled medication or a banned substance depending upon the governing association. Because of this, extreme care should be exercised when administering CBD to competition horses.

^*Interlandi, C., M. Tabbì, S. Di Pietro, F. D’Angelo, G.L. Costa, F. Arfuso, E. Giudice, P. Licata, D. Macri, R. Cupri, and E. Gugliandolo. 2024. Improved quality of life and pain relief in mature horses with osteoarthritis after oral transmucosal cannabidiol oil administration as part of an analgesic regimen. Frontiers in Veterinary Science 11:1341396.