Can they eat it? / Lily of the valley
Can horses eat lily of the valley?
Never. Heart toxin in every part.
A shade garden plant; keep garden waste out of paddocks.
Irregular heartbeat, weakness, colic.
Call your vet now. Note what was eaten, how much and when; do not wait for signs.
Why it is dangerous
Lily of the valley (Convallaria majalis) contains cardiac glycosides, compounds similar to those in foxglove, that act directly on the heart muscle. They slow and disrupt the heartbeat and can cause dangerous rhythm problems. Every part of the plant carries these toxins, including leaves, stems, flowers, berries and roots, and they stay active when the plant is dried, wilted or mixed into hay or clippings.
How much is too much
For a 1,000 lb horse there is no safe amount. Even a small mouthful of leaves or a few berries can be enough to cause harm, and a handful is a serious exposure. The toxin load is hard to judge by eye, so treat any contact with the plant as an emergency. The same applies to ponies, miniatures and metabolic horses, who may react to smaller quantities and can become unwell faster.
Horses
Full-size horses in work or at pasture are at risk from garden clippings, thinned shade beds, and plants growing along fence lines or in woodland edges where turnout occurs. Many horses avoid bitter plants, but they may still eat them when grazing is thin or when cut material is dropped in a paddock. Check any area near shade gardens, and keep yard waste and compost out of reach.
Ponies and easy keepers
Ponies, miniatures, seniors and insulin-resistant or laminitis-prone horses can be drawn to sweet-looking plants and may eat more than they should. Their smaller body size also means less margin for a toxic dose. Keep these animals away from lily of the valley entirely, and check that companion grazing areas and feed rooms contain none of the plant.
Safe alternatives
Offer good-quality grass hay, a measured portion of hay pellets or chaff, or a small amount of fresh grass if your horse is allowed it. For a treat, use a few pieces of carrot or a handful of a plain forage cube, served in a clean bucket and kept away from the plant bed.
Questions people ask
Is lily of the valley dangerous in hay?
Yes. The toxins remain active when the plant is dried, so it is dangerous in hay. Check hay before feeding and remove any plant material you see.
Can a horse eat lily of the valley after frost?
Frost does not make it safe. The plant stays toxic through the seasons, so keep horses away from it at all times, whatever the weather.
My horse ate some lily of the valley, what should I do?
Call your vet now, even if your horse looks well. Note what was eaten, how much and when, and do not wait for signs to appear.
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.