Plants Poisonous to Horses, and the Rules on Ragwort

Why Horses Eat Plants They Shouldn't

Most horses avoid bitter, poisonous plants when there is plenty of good grass. Trouble starts when fields are bare and hungry horses pick at whatever is left, when poisonous plants are cut and wilted (some taste better then), or when they end up dried in hay, where horses can't sort them out.

So the best protection is good grazing, plenty of forage, and keeping poisonous plants out of fields and hay altogether. See grazing and pasture management.

Ragwort: The Big One in the UK

Common ragwort is a tall plant with flat-topped clusters of yellow, daisy-like flowers in summer, growing from a rosette of ragged leaves in its first year. It is poisonous to horses, ponies, cattle and sheep, and it stays poisonous when dried, which makes ragwort in hay or haylage especially risky.

• Pull or dig it out before it seeds, getting as much root as you can. Wear gloves.
• Never leave pulled plants in the field. Wilted ragwort is more tempting.
• Dispose of it safely. gov.uk says small amounts can rot down in a lidded container such as a compost bin; larger amounts need a permitted site or a registered waste carrier.
• Check your hay supplier's fields and reject hay with ragwort in it.

Trees and Hedges to Watch

• Yew: extremely poisonous, including clippings and dried leaves. Fence it well out of reach, and never throw hedge trimmings into a field.
• Oak: acorns, and young leaves, are a risk in autumn and after storms. Some horses develop a taste for acorns. Fence off or collect them in heavy years.
• Sycamore and box elder (its North American relative): seeds and seedlings carry a toxin linked to a serious muscle condition in grazing horses. Seedlings often carpet fields in spring. Fence off, collect seeds, and ask your vet about the risk on your land.
• Red maple (North America): wilted or dried leaves are the danger, especially after storms bring branches down.
• Laburnum, privet, laurel and rhododendron: common garden and hedge plants that are poisonous to horses.

Field and Garden Plants

• Bracken and horsetail (marestail), in fields and in hay.
• Foxglove, hemlock and deadly and woody nightshade, in hedgerows and field margins.
• Buttercups, which horses usually avoid when fresh; they are much less of a worry once dried in hay.
• Oleander (warmer climates, often planted in gardens): very poisonous even in small amounts, including dried leaves.
• Garden waste of any kind. Lawn clippings, hedge trimmings and garden plants should never be fed to horses or tipped over the fence.

This isn't a complete list, and what grows depends on where you live. A local vet, a grassland adviser or your national horse welfare charity can tell you what to look out for.

Bedding and Hay

Black walnut shavings can harm horses even as a small part of the bedding, so buy shavings sold for horses from a supplier who can tell you the wood. Buy hay from fields you can trust, and look through each bale for weeds, mold and dust as you feed it.