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Cannabidiol, otherwise known as “CBD,” is the latest alternative health trend to go mainstream. CBD products are gaining popularity as alternative or complementary treatments for a variety  of conditions in people and animals, including epilepsy, anxiety and osteoarthritis. 

Yet many questions about CBD use in horses remain.  How does it affect a horse’s physiology? What’s the best mode of administration? Can you trust claims that CBD can soothe your horse’s stress and even relieve his pain?

Researchers are still working to understand CBD and investigate its potential benefits and risks. But that doesn’t mean you have to wait to explore whether it can keep your horse calm or comfortable.

To help you determine whether a CBD-based product might be right for your horse, we’ve enlisted the help of holistic veterinarian Joyce Harman, DVM, a leading authority on equine acupuncture and alternative medicine.

The cannabis connection

CBD is derived from cannabis plants, a genus cultivated around the world for thousands of years. Archeological evidence suggests that cannabis plants, which originated in Asia, were used by humans  as early as 2800 BCE.

There are two main species of cannabis, and many strains within those related species. Hemp-type cannabis includes varieties traditionally cultivated for their fiber (rope, twine, etc.);  seeds (for food); and oils. Other types of cannabis, classified as marijuana strains, have been used for centuries for ritual, medicinal and recreational purposes.

The active ingredients in all these plants are chemicals called phytocannabinoids. The marijuana strains of cannabis plants are cultivated to produce high levels of tetrahydrocannabinol (THC), a psychoactive (mind-altering) phytocannabinoid. By comparison,  the Hemp strains, which contain cannabidiol (CBD), are not considered psychoactive. Studies in people and animals suggest that cannabidiol can relieve anxiety, reduce inflammation and provide pain relief. It is also prescribed to treat some types of epilepsy. 

CBD vs. THC

“The difference between hemp and a marijuana plant is the amount of THC,” explains Harman. “The plants we want for our animals are hemp plants. They have been selected and cultivated for high CBD and little to no THC.”

Why are CBD products just now flooding the U.S. consumer markets? It all started when the Agriculture Improvement Act  of 2018 removed industrial hemp from  the definition of marijuana in the Controlled Substances Act (CSA). Once hemp was legally separated from its psychoactive cousin, new uses of the plant became economically feasible. Nonetheless, regulations governing CBD are constantly changing, with different states taking different approaches to the sale of CBD products. That means that you’ll want to keep up to date on your state and local laws.

Calming effects

One of the primary claims made about CBD centers on its calming effects. Instead of the psychoactive “high” conferred by the THC in marijuana, CBD is believed to soothe stress or anxiety.

“There is human research in post-traumatic stress disorder (PTSD) and stress showing that those problems improve with CBD,” Harman says. “Many horse owners and veterinarians have seen positive responses from animals that have been through stressful periods. It helps with mental equilibrium.”

CBD interacts with the body’s endocannabinoid system, which regulates many physiological functions, including appetite, mood, pain sensation and immune response. By binding to certain receptors in the endocannabinoid system, CBD can help modulate these functions. “CBD doesn’t make horses ‘stoned’ like THC would,” explains Harman. “The brain is still functioning normally. The horse is calm but if there is cause to be alert, the horse is still capable of being alert.”

Although these calming effects have yet to be proven in clinical studies, Harman sees horses as good candidates for trial therapy with CBD. After all, modern management practices can place horses under constant stress. Equine athletes are sometimes confined in small spaces, separated from their social groups and asked to do things that don’t come naturally to them. “Many horses are on edge all the time. When we get on them, they spook at everything,” Harman says. “CBD can help them to stay calm, to ‘forgive and forget.’”

Inflammation  and pain

CBD also shows promise for treating chronic pain in horses. As Harman wrote in a 2020 article in Innovative Veterinary Care Journal, “Cannabinoids have action in both acute and chronic pain by modulating pain signals in the central and peripheral nervous systems and acting similarly to an anti-inflammatory.” Cannabinoids can also act as antioxidants and support immune function, she says.

Therapy incorporating CBD may be beneficial for treating a variety of equine conditions, says Harman. These include laminitis; insulin resistance; musculoskeletal pain (such as arthritis); chronic skin disease; chronic ulcers; uveitis; and even Lyme disease. CBD is currently most often used to treat musculoskeletal pain—primarily arthritis and other lameness issues. Though rarely the only treatment a horse receives, CBD may offer pain relief without the potential side effects of long-term use of conventional anti-inflammatory drugs like phenylbutazone (bute).

Keep in mind that CBD’s effectiveness against chronic pain has yet to be scientifically proven. It also appears to vary greatly among individual horses. Still, many people, including Harman, advocate trying CBD, particularly in cases where traditional treatments have failed to alleviate persistent pain.

Pellet, powder  or oil?

CBD products for horses come in three forms: pellets, powders and oils. “If you are selecting a powder rather than pellets, the powder should be 100 percent hemp, with nothing else added,” advises Harman, noting that  like the pellets, powders are easily  incorporated into a horse’s feed. Pellets often have added mold inhibitors or  alfalfa to help make the pellet.

Then there are the oils. “[CBD] is extracted from the plant, then mixed with an oil base,” Harman says. “Any kind of safe, healthy oil is fine to dilute it in—usually hemp seed oil or MCT oil (from coconuts)—to get an amount you can measure in a dropper for feeding.”

Some people claim that rubbing the CBD-infused oil into a horse’s gums is the fastest way to get cannabidiol into his system. However, Harman says it is often more practical to add CBD to feed. What’s more, recent studies show suggest that it is better absorbed when administered with food. The oil can also be put straight into the mouth with a dropper.

“Some product [labels] say they are water-soluble. They get into the system better,” Harman says, which might be useful just before a trail ride, for example. “It does go into the system faster, but this may not be critical with long-term use,” she notes.

How much to feed

The amount of CBD needed to achieve the desired effect in horses varies. Each individual responds differently to  the compound. Nonetheless, with  CBD—as with any supplement or medication—it’s important follow  the manufacturer’s directions.

Fortunately, says Harman, CBD has a relatively solid safety record in many species. It also seems to be well tolerated by horses in preliminary studies: “One thing we know about CBD is that the parts of the brain it works on will not be adversely affected by overdose.”

Still, it’s wise to be cautious about giving your horse too much CBD. Research has shown that higher doses of CBD can change liver enzyme levels in people and animals, though these may not be a problem, according to some recent studies. There are no specific studies in horses but it is wise to be aware of this. Preliminary data coming from ongoing studies is showing that very high levels can be tolerated well in many species.

Minimum and maximum amounts

Therefore, you’ll want to establish the smallest effective amount of CBD for your horse and stick with that. “I recommend starting at about 25 milligrams for about a week or 10 days. If you are not seeing improvement in the condition you are trying to help, then double the amount (50 milligrams) for a while,” Harman says. “If that’s still  not working, you can go higher until  you find the level that works in that particular horse.”  Some products recommend starting with higher amounts. It best to follow manufacturer’s instructions as the quality or concentration can vary considerably.

In contrast, says Harman, a large loading (initial) dose might be worthwhile when administering CBD to combat inflammation and discomfort related to arthritis. “You might start at 50 milligrams for a week and increase it if necessary—on up to 200, if need be, and stay there for a few weeks or a month,” she says. “If the horse becomes sound and is no longer in pain, you could back down until you find a comfortable level.”

If maximum doses of different CBD products don’t produce the desired results in your horse, it’s time to look for other alternatives. Regardless of the hype, Harman stresses that CBD isn’t a cure-all, and it won’t help every horse.

Potential downsides

The potential benefits of CBD are clear. But there are also possible downsides.

One concern comes from the fact that rules and regulations governing CBD products are often unclear and are still evolving. Although the Food and Drug Administration (FDA) has approved a CBD prescription medication for treatment of certain types of seizures, the agency has declined to issue rules for other CBD products.

 “It is not apparent how CBD products could meet safety standards for dietary supplements or food additives,” said FDA Principal Deputy Commissioner Dr. Janet Woodcock in a statement explaining the decision. The same statement goes on: “The use of CBD  raises various safety concerns, especially with long-term use. Studies have shown the potential for harm to the liver, interactions with certain medications  and possible harm to the male reproductive system. CBD exposure is also concerning when it comes to certain vulnerable populations such as children and those who are pregnant.” The FDA is calling on Congress to establish a regulatory structure to ensure the safety and efficacy of CBD products.

Regulatory gaps

Until those regulatory gaps are bridged, Harman advises sticking with CBD products offered by well-established companies that are transparent about their ingredients and production standards. When you see inexpensive CBD products, she says, consider that “there is often a reason they are so inexpensive.”

Keep in mind that most horse-sport organizations prohibit anything that might alter or enhance performance, including CBD. That means that horses may be tested for CBD along with other banned substances.

To stay in compliance with competition rules, Harman suggests administering CBD between events. “We don’t know yet what a safe withholding time would be for all horses,” she says.  “So that no one gets into trouble using CBD in horses, we recommend [withdrawing the horse from CBD for] seven days [prior to competition].”

Horses that compete less often, as well as those in rehab or on a break from competition, may benefit from CBD administered during “down” periods. Then, “if your horse is functioning in a calmer way, you may have improved the condition of his endocannabinoid system,” Harman says.

Shopping tips

As with any supplement, it’s best to purchase CBD supplements only from well-regarded companies. “Reputable companies use organically grown hemp for their CBD products, but certification of organic status has only recently been granted to the hemp industry,” Harman points out. “Some products are grown responsibly, using organic methods, but are not certified as organic yet because the process is expensive and can take several years for a farm to obtain.”

Certificate of analysis

A reputable company selling CBD products will also publish a COA (certificate of analysis) for each product on its website, verifying that it has paid to have these products tested. The COA lists everything in the product: the cannabinoids, any terpenes (other beneficial plant compounds), any solvent contamination, heavy metals, other chemical residues and microbiology—as well as any molds or bacteria.

It’s smart to consider how a product was processed, as well. “CBD can be safely extracted using carbon dioxide (CO2) or high-quality, organic ethanol,” Harman explains. “The cheap way is to use some nasty chemicals like benzene. Your local gas station or convenience store might sell CBD, but you may be getting other chemicals along with it.” The COA will tell you whether there are residues left over from processing and whether the plants were grown in soils free of heavy metals or other contaminants. “It will also tell you the strength (actual amount) of CBD in  the product,” Harman says.

THC content

In addition, you’ll want to verify that the product contains little to no THC, which can occasionally be present in trace amounts. The legal amount of THC to be in a CBD product is 0.3% and that amount will have no psychoactive effect. While Harman says that THC might be helpful in horses with cancer, dogs are highly sensitive to it, and “we don’t know enough about THC to recommend its use in [otherwise healthy] horses.”

Our expert

Joyce Harman, DVM, has more than 30 years of experience in holistic veterinary medicine. She is the founder and owner of Harmany Equine Clinic in Flint Hill, Virginia. After receiving her veterinary degree from the Virginia-Maryland Regional College of Veterinary Medicine in 1984, Harman decided to explore alternative approaches to animal health. Over the years, she has incorporated a variety of holistic modalities into her practice, including acupuncture, herbal medicine, homeopathy, CBD and chiropractic care. Her website contains educational material, and she is currently working on an online nutrition and holistic health course. Harman is the author of The Horse’s Pain-Free Back and Saddle-Fit Book and is a sought-after speaker on veterinary topics around the world.