Can they eat it? / Tansy ragwort
Can horses eat tansy ragwort?
Never. The same slow liver poison as other ragworts.
Widespread in the Pacific Northwest. Pull it before it flowers.
Weight loss, photosensitivity, yellow gums, odd behavior, months later.
Call your vet for a liver check.
Why it is dangerous
Tansy ragwort contains pyrrolizidine alkaloids, which the horse's liver converts into toxic compounds that slowly destroy liver cells and block normal blood flow through the organ. Damage builds up gradually, so a horse can eat a little each day and show no obvious trouble for weeks or months. Dried ragwort in hay is just as dangerous as fresh, and it tends to be less bitter, so horses may eat it without hesitation.
How much is too much
For a 1,000 lb horse there is no safe amount of tansy ragwort, because the damage is cumulative and a small daily nibble adds up over time. A single mouthful may cause no visible harm, but every bite adds to the liver load. Ponies, miniatures and metabolic horses are not safer; their smaller body size can make even modest intake more dangerous. Treat any intake as a reason to act.
Horses
Horses in work or at pasture are most at risk when ragwort grows along fence lines, field edges, ditches or in overgrazed paddocks where horses have few other choices. Check pastures regularly and pull plants by the root before they flower and set seed. Wear gloves, bag the plants and dispose of them rather than leaving them piled where animals can reach them. Hay from fields with ragwort should be inspected.
Ponies and easy keepers
Ponies, miniatures, seniors and easy keepers may be drawn to ragwort in lush grass and can be harmed by smaller amounts. Keep these animals in ragwort-free paddocks and check any grazing area before turnout. Older horses with reduced liver reserve have less margin for error. If you suspect exposure, your vet can discuss liver monitoring tailored to your horse's age and health.
Safe alternatives
Offer good-quality grass hay, a measured flake of alfalfa or timothy, or a safe pasture with abundant grass and no weeds. Keep fresh water available and rotate paddocks to reduce grazing pressure. Ask your local extension office about grasses suited to your region.
Questions people ask
Is ragwort dangerous in hay?
Yes. Dried ragwort stays toxic and horses may eat it without picking around it. Inspect hay carefully and buy from sources that control weeds.
My horse ate some ragwort. What now?
Call your vet and ask about a liver check, even if your horse looks well. Damage can be silent for weeks or months.
Can I remove ragwort safely?
Wear gloves, pull plants by the root before flowering, bag them and dispose of them away from pasture. Do not burn or compost them where horses can reach.
Toxic for horses means: do not give it; if they ate it, call your vet or a poison line.
General information from veterinary guidance, not a diagnosis. If you are worried, call your vet or a pet poison line: ASPCA Animal Poison Control (888) 426-4435. Charges may apply.
Written by Hoofdeck editors · updated Nov 13, 2026 · from ASPCA Animal Poison Control, Merck Veterinary Manual and university extension guidance.