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What a Stereotypy Actually Is
Cribbing — gripping a solid edge with the incisors, arching the neck and drawing air in — is the one horse owners know by name. It sits alongside weaving, stall-walking, head-bobbing, box-walking and persistent pawing in a category researchers call stereotypic behaviour: repetitive, apparently functionless movement patterns with no obvious goal.
The older language for these was "stable vices," which framed them as a character flaw. Current thinking treats them as the opposite: a coping response to an environment that does not let a horse do what a horse does. The consistent risk factors in the literature are confinement, limited turnout, restricted forage and concentrate-heavy diets — conditions that compress a grazing animal's 16-hour foraging day into two meals. The Horse keeps a useful running summary of where cribbing research has got to.
That framing matters before any supplement conversation, because it tells you where the leverage is. A horse cribbing in a stall for 22 hours a day has an environment problem first.
What Our Study Measured — and What It Found
We funded behavioural work on our own equine formula at Tarleton State University (Texas A&M System), led by Dr. Kimberly Guay, Ph.D. at the Equine Center. It was published as a peer-reviewed abstract: Turner PL, Guay KA, Jones T, Cohen L, Elwonger F, Van Geem R, Smith WB, "The Effects of Feeding Cannabidiol Oil on Behavior of Stalled Horses," Journal of Animal Science 2021;99(Suppl. 3):5.
The design: eight stock-type horses — four mares, four geldings — randomised across an olive-oil control and two dose levels, 0.3 mg/kg and 0.6 mg/kg of body weight, given orally. Behaviour was scored from video using Observer XT and analysed in R.
| Behaviour counted | Control | High dose (0.6 mg/kg) |
|---|---|---|
| Aggression | 113 | 26 |
| Pawing | 69 | 27 |
| Stereotypic behaviours overall | Significantly lower on CBD, P = 0.03 | |
The authors' conclusion was that CBD "may mediate negative behaviors in stalled horses." Behaviours clustered around feeding sessions — which fits the forage-restriction picture above rather than cutting against it.
Three limits we are not going to bury.
Eight horses. This is a peer-reviewed conference abstract on a small sample, not a multi-centre trial. It is a signal worth acting on cautiously, not proof.
The daily course did not work. The same project also ran a five-day daily-dosing arm. In the investigator's own summary of it, with daily dosing over five days "there was no difference in behavior between the control and the CBD dose." The significant result above came from single-dose administration. If you take one practical thing from this page, take that one — it points to dosing ahead of a specific stressor rather than keeping a horse on a standing daily course for behaviour.
Cribbing itself was not measured. The behaviours counted were aggression, pawing and other stereotypies. Cribbing was not an endpoint. Dr. Guay's own list of remaining work includes recording additional horses specifically for stereotypies such as cribbing — meaning that study has not been done. Anyone telling you hemp is shown to reduce cribbing is going past the evidence, and so would we if we said it.
Management First. Genuinely.
Every credible source on stereotypies puts environment ahead of everything else, and a supplement company saying otherwise should lose your trust:
- Turnout. More hours out, ideally with company, is the single most consistent change in the literature.
- Forage availability. Small-hole nets, more frequent hay, slowing intake so the foraging day stretches back out.
- Fewer concentrates where the workload allows, since grain-heavy diets track with higher stereotypy risk.
- Company and sight lines. Visual and social contact with other horses.
- Enrichment in the stall for horses who genuinely must be confined — box rest after injury being the common case.
A cribbing strap suppresses the behaviour without addressing why it is happening, and researchers generally treat suppression as the least good option. If a horse has started cribbing suddenly, that is a veterinary conversation before it is a management one — gastric ulceration and dental pain both belong on the list.
Where Hemp Fits
Honestly: as a possible support for a horse who is already managed as well as circumstances allow, most plausibly around a known stressor. Box rest after an injury, a change of yard, weaning, a farrier or dentist visit, a horse who winds up in the hours before shipping. That is the shape our single-dose finding actually supports.
What it is not: a substitute for turnout, and not a treatment for cribbing.
How much, and when
The doses used in the behavioural study were 0.3 and 0.6 mg/kg of body weight, with the larger effect at 0.6 mg/kg. For a 500 kg horse that upper figure is about 300 mg of CBD in a single administration — which is why equine products are concentrated and why dog bottles are not a sensible way to dose a horse.
There is a published reason horses need so much: in a crossover study in senior horses, oral bioavailability of CBD came out at 7.92%, with a single-dose half-life of 7.22 ± 2.86 hours and peak plasma at about 2.5 hours. Separate pharmacokinetic work on our own formula found plasma levels peaking around 1 to 4 hours and back to baseline by 16 to 24 hours. So for a known stressor, giving it one to four hours ahead is the window the data points at.
Our equine formula is the product that was studied: 5,000 mg of full-spectrum hemp extract in cold-pressed virgin olive oil, delivering roughly 20 mg per half-cc pump. Confirm the amount for your horse with your own veterinarian, who knows the animal and what else it is on.
How to give it
Pumped onto feed is the practical route and the one used in the research. Cannabinoids are fat-soluble, so giving it with a feed containing some fat helps absorption. Horses vary in how much they object to the taste of an oil; mixing it into a small damp feed rather than dry hay generally works better.
Sourcing and quality
Independent testing of over-the-counter hemp products has repeatedly found label claims that do not match contents, so the certificate of analysis is the only thing worth trusting. Look for full-spectrum extract with the milligrams per millilitre stated, US-grown hemp under 0.3% THC, and current third-party results — ours are published at lab results, and our encyclopedia explains what a certificate of analysis shows.
Side effects and cautions in horses
The dose-study abstract from our own project concluded that "this one-time orally-administered dose of CBD oil resulted in no adverse effects in horses at neither 0.3 nor 0.6 mg/kg." The independent literature on longer courses is where the cautions live, and horse owners should know them:
- Liver enzymes. In a controlled study of 12 horses given loading doses then 0.5 or 1.5 mg/kg twice daily for six weeks, elevated liver enzymes were seen in 8 of 12 horses — all of which normalised within 10 days. Mild hypocalcaemia was seen in all horses. The same enzyme signal shows up in dogs, and we go through every canine dataset in our guide to hemp and CBD side effects in dogs.
- Insulin response. A 21-day study in Connemara ponies, including several with equine metabolic syndrome, found the supplement well tolerated but flagged an increased insulin response. If your horse is EMS-prone or insulin-dysregulated, that is a specific conversation to have with your vet before starting.
- Interactions. As in other species, cannabinoids can affect how the liver handles some medications. Tell your vet what your horse is on.
See a veterinarian before starting if your horse is on medication, is insulin-dysregulated or laminitis-prone, is pregnant or lactating, or has known liver disease — and promptly if a stereotypy appears suddenly, worsens quickly, or comes with weight loss, colic signs or a change in appetite.
Competition Rules: Read This Before You Buy
If your horse competes, this section may be the whole answer.
CBD is prohibited in competition. USEF has treated cannabinoid positives as GR4 violations since 1 September 2019 and accepts no medication report form for them. USEF's own guidance states that CBD is prohibited under FEI, HISA and USEF rules. Enforcement is real, not theoretical — a 2019 Kentucky case resulted in a 30-day suspension, a fine, disqualification and forfeited purse.
And there is no validated withdrawal time. This is the part almost nobody explains properly. A single dose clears in hours — half-life about 7 hours. But CBD is fat-soluble, and daily dosing for two to three weeks loads fat tissue, which then releases it slowly: pharmacokinetic modelling after 3 mg/kg twice daily for 15 days found a terminal half-life of 161 ± 44 hours, with the terminal phase not even beginning until around 132 hours after the last dose. Clearance depends on how long you have been dosing, not just how much. Because no effective dose has been established, no screening limit or detection time can be calculated — so any confident "withdraw X days before a show" figure you see is invented.
Practical reading: this is better suited to pleasure horses, retired horses, and horses on box rest out of competition. If your horse competes under USEF, FEI or HISA rules, do not use it, and verify current rules yourself rather than taking a retailer's word — including ours.
Frequently Asked Questions
What is the best calming supplement for a horse on stall rest?
There is no single best one, and the honest order of operations puts management first — forage availability, company, sight lines and enrichment do more than any supplement. Among supplements, the ingredients with the most equine evidence behind them are limited, and full-spectrum hemp has one small peer-reviewed behavioural abstract in stalled horses (our own, described above) rather than a body of literature. Ask your vet, and be sceptical of anything claiming certainty.
How much CBD do you give a horse?
The behavioural study used 0.3 and 0.6 mg/kg of body weight orally, with the larger effect at 0.6 mg/kg — roughly 300 mg for a 500 kg horse. Oral bioavailability in horses is low (measured at 7.92% in one crossover study), which is why equine doses look so much larger than canine ones. Confirm the amount with your veterinarian.
Does hemp stop cribbing?
We cannot say that and the research does not support it. Cribbing was not one of the behaviours measured in our study; the endpoints were aggression, pawing and other stereotypies. A study specifically on cribbing has not been completed. Management remains the first-line approach.
What is the best hemp for a horse that gets anxious?
Look for full-spectrum extract rather than isolate, milligrams per millilitre stated on the label, a current third-party certificate of analysis, US-grown hemp under 0.3% THC, and a concentration high enough to dose a 500 kg animal without half a bottle. Our own formula is the one used in the Tarleton research, which is the only claim of that kind we can make.
Are there sedatives for horses on stall rest?
Sedation is a veterinary decision and a prescription matter — not something to approach through a supplement. Full-spectrum hemp is not a sedative and should not be used as one; the goal is a calmer, more settled horse that is still fully itself. If a horse genuinely cannot cope with box rest safely, that is a conversation with your vet about a plan, which may include prescription medication.
Can I give it every day?
You can, and the tolerability data on longer courses is reasonably reassuring with the liver-enzyme and insulin cautions above. But for behaviour specifically, the five-day daily arm of our own project showed no difference, while single-dose administration did. So daily dosing is not what our evidence supports for this purpose.
Will it show up on a drug test?
Yes, and there is no published withdrawal time. See the competition section above.
Sources
- Turner PL, Guay KA, Jones T, Cohen L, Elwonger F, Van Geem R, Smith WB. "The Effects of Feeding Cannabidiol Oil on Behavior of Stalled Horses." J Anim Sci 2021;99(Suppl. 3):5. doi:10.1093/jas/skab235.008
- Yocom AF, O'Fallon ES, Gustafson DL, Contino EK. Pharmacokinetics, safety and synovial fluid concentrations of single- and multiple-dose oral administration of CBD in horses. J Equine Vet Sci 2022.
- Single- and multiple-dose pharmacokinetics of cannabidiol in senior horses. Am J Vet Res 2022;83(9).
- Pharmacokinetic modelling of cannabidiol for medication control in horses. Front Vet Sci 2023.
- Cannabidiol supplementation in Connemara ponies. Front Vet Sci 2026.
- United States Equestrian Federation guidance on cannabidiol and GR4 prohibited substances.
More on both of our university trials, including the canine osteoarthritis study, is on our clinical trials page, and the full equine write-up is at our equine research page. If you want to see how the equine numbers compare with the canine side, we assembled every dose used in the five published dog trials side by side — protocols, durations, outcomes and the liver-enzyme findings.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. Research doses described here are reports of study protocols, not serving recommendations. Always consult your veterinarian before starting any new supplement, especially if your horse is taking medication or has a health condition. If your horse competes, check current USEF, FEI and HISA rules — cannabinoids are prohibited.
