Wild (and cultivated) Hemp (Cannabis sativa)
Cannabis sativa
Horse
Moderate
Call the vet within four hours, even without symptoms. A few hundred grams of leaves or flowering tops.
Equio informs, it does not diagnose. When in doubt, call your vet.
What to do now
- Antidote
- No specific antidote. Symptomatic and supportive treatment.
- Time to signs
- 30 minutes to a few hours
- Prognosis
- Good. Equine metabolism eliminates the toxin in 24 to 48 hours. Deaths from respiratory arrest are very rare except with astronomical doses.
- Secure the horse in a padded stall or a very quiet enclosed area.
- Reduce light and sound stimulation.
- Closely monitor intestinal transit.
- Call the veterinarian if heart rate plummets.
Its ID card
- Height
- 0.5 m – 3 m
- Flowering
- July to October
- Toxic parts
- Leaves and flowers (seeds/hempseed and stem fibers are safe).
- Toxin
- Cannabinoids (THC, CBD, etc.)
- Habitat
- Agricultural fields (textile hemp), wastelands (wild hemp), dumped waste.
- Soil indicator
- Loose, cool soils, very rich in nitrogen.
- Regions
- Europe (Industrial crops, wastelands, gardens)
- In hay
- Yes — stays toxic once dried
- Palatability
- Medium. Intoxication often comes from involuntary access to an agricultural crop or discarded waste.
When the risk rises
August to October (flowering, maximum resin production).
Spotting it in the field
Few confusions possible (iconic leaf shape). — smell : strong, resinous, and aromatic odor, particularly pronounced when handling leaves and flowers.
- Large, vigorous herbaceous plant (up to 3m).
- Characteristic palmate leaves composed of 5 to 9 long, narrow, toothed leaflets.
- Very typical strong, resinous aromatic odor.
Signs to watch for
Acute toxicity.
Dose : Several hundred grams of leaves or flowers for a 500 kg horse.
- Profound drowsiness, apathy (very low head, 'disconnected' horse)
- Severe incoordination (horse staggers as if drunk)
- Hypersalivation or, conversely, great dry mouth
- Mild tremors and skin twitching
- Heart and digestive slowing (risk of colic)
Who is affected
Other species : Extremely toxic (and common) in dogs (ingestion of cigarette butts, resin, or crop waste) causing comas.
In pregnant mares : can cross the placental barrier, absolutely avoid.
Getting rid of it
Method : Uproot the entire plant before flowering, wearing gloves. Destroy waste by incineration.
- Avoid grazing in areas where hemp is cultivated or has been recently harvested.
- Never feed hemp crop leftovers to a horse.
- Be vigilant about waste potentially contaminated with hemp.
Frequently asked questions
Can Equio identify Wild (and cultivated) Hemp (Cannabis sativa) from a photo?
It can help organize visual clues, but plant identification must remain cautious when horse health is at stake.
Is Wild (and cultivated) Hemp (Cannabis sativa) dangerous in hay?
This entry flags hay vigilance. Isolate suspicious forage and ask for professional advice if exposure is possible.
This page is informational. If ingestion is likely, if signs appear, or if the horse is fragile, contact a veterinarian immediately.