Poisonous Plants

This page applies particularly to horse and pony pasture, reflecting plants that have unwanted effects in horses and ponies (equine).

Everyone knows that Ragwort is extremely dangerous, to those few horses that will eat it. It may not be so well-known that, should the plant be damaged and wilted, horses may be attracted to it. Haymaking that accidentally incorporates Ragwort is very dangerous because of this palatability-enhancing effect, inherent in the haymaking process. It may also not be well-known that Ragwort is a biennial plant and that the first-year phase is a low, rosette-like plant (rather than the tall, second-year flowering phase), close to the ground and not easy to see, except on bare ground. Ragwort plants must be uprooted and destroyed. Even accidental breaking or crushing of ragwort in a field, by tractor wheel or horse hoof, can be dangerous as the damaged plant then wilts and becomes palatable.

Horses will generally avoid eating poisonous plants but, should grass ‘burn off’ in the summer, or should horses be in an over-crowded, over-grazed field, then they may develop a desire to forage in the hedgerows and to eat what they would normally shun. Fibre-deficient horses can also browse avidly and with poor discrimination. Poisonings can then occur.

More poisonous or undesirable plants are known, than the examples listed below. Basic knowledge of plants and their recognition is therefore important. The AVMC is happy to advise on this important aspect of grazing management, if required.

While horses and other herbivores are obviously in a situation where they may be exposed to poisonous plants and may perversely wish to eat them, it is not unknown for other species (e.g. dogs and cats) to ingest poisonous plants and to suffer ill effects. Many house plants, for instance, are capable of causing digestive upsets, colic or more serious poisonings. The flowers and shrubs that we keep in our gardens may also be hazardous. Despite the widespread distribution of toxic plants in the domestic environment, it has to be said that poisonings are, happily, very rare. The signs and symptoms suffered by a German Shepherd Dog having eaten Bryony were once reported in detail in the ‘Veterinary Record’. The AVMC has treated several puppies that have mischievously or playfully eaten daffodils and other house plants. The Labrador pup that ate the daffodils became uncoordinated and fell down the stairs. He luckily survived both challenges.

It pays to be able to recognise the more common poisonous plants that your animals may encounter. For this reason, we have published a gallery of photographs as an aid to recognition.

Poisonous Plants (some examples, including trees and fungi):

Aconite (Monkshood)

Black Bryony

Bracken

Deadly Nightshade

Death Cap

Dog’s Mercury

Dropworts (various)

Ergot, in rye grass etc.

Flax (see Linseed)

Fly Agaric

Foxglove

Hellebore

Hemlock

Henbane

Horsetails

Jack-in-the-Pulpit

Laburnum

Laurel

Lily of the Valley

Linseed (uncooked)

Meadow Saffron

Mezereon

Mouldy hay

Privet

Ragwort

Rhododendron

St John’s Wort

White Bryony

Yew (tree)

Buttercups

Clematis

Clover (esp. White and if in excess)

Elderflower

Grass clippings

[Hay or grass that has been fertilised with artificial nitrogen]

Haylage

Oak (acorns)

Rape

Sugar Beet

Woody Nightshade

Grass, when artificially fertilised, can be a hazard for horses. Oven-dried grass, Silage or Haylage are not good for digestion. Grass clippings can be a real danger.

Yew: One particular hazard that may unwittingly cause tragedy is the provision of grass clippings incidentally or accidentally containing yew clippings, from ornamental trees or from a churchyard. People operating lawn mowers, hedge trimmers or clippers do not always realise the lethal significance of such things for horses.

Nettles, when sprayed and at the wilting stage, even if so-called ‘livestock-friendly’ herbicides have been used, can cause serious laminitis or worse. By way of contrast, unsprayed, wilted nettles are a wonderful food for horses.

Clients of AVMC are given deeper advice on this vital topic, with explanations, on request.

Other words: toxic - toxin - noxious - toxins - herbs - herbage - forage - hay - haylage - grass - grassland - pasture - pastureland - grazing - herbage - horse - horses - pony - ponies - donkey - donkeys - equine - equines