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A guide to poisonous plants for horses and ponies

- Posted by in Pet Care
A guide to poisonous plants for horses and ponies

Turning out our horses is something most of us do without thinking about. But what hidden dangers are our horses sharing their fields with? Many plants, trees and hedges are poisonous to horses and ponies when ingested and not all are easy to recognise.

To avoid poisoning, it is important to be able to differentiate harmless plants from highly toxic ones in your horses’ paddocks. Some of the most common poisonous plants and trees are listed below so if you happen to detect any of these in the field, pull them up by the root and burn them so the pollen cannot spread.

If you are thinking about using herbicides, speak to a professional before allowing your horses back in the paddock afterwards. It is always best to wait until heavy rainfall has washed the chemicals away before doing so. Any poisonous trees and hedges should be fenced off so their overhanging leaves don’t pose a danger to horses grazing nearby.

Because the effects of most poisonous plants are cumulative, it isn’t always easy detecting a problem until it is too late. If symptoms do show, they are likely to include breathing difficulties, restlessness, lethargy/depression, loss of appetite, convulsions and visible signs of pain.

Ragwort rosette stage

1) Ragwort is a poisonous plant that produces lots of highly toxic seeds, which are easily and widely dispersed by the wind. Horses don’t need to consume much of this plant to suffer liver failure and complete deterioration. In fact, ragwort is toxic enough to also pose a threat to humans, so make sure you always wear gloves when handling it.

The effects of ragwort accumulate over a period of time, leading ultimately to catastrophic symptoms. Because younger plants are believed to taste less bitter than mature ragwort, it is likely that horses consume more of it without realising. Dead ragwort is just as toxic to a horse as the living plant, so make sure that hay and haylage isn't harbouring it.


Ragwort starts appearing from early spring onwards and is instantly recognisable for its long green stems stretching up to bright yellow rosettes. Ideally, ragwort should be removed before it flowers and this is best done after rainfall when the ground is soft and plants can be pulled up by their roots.


2) Hemlock is a common weed found in fields and is characterised by long stems (growing over 6 ft tall), with purple spotting and small clusters of white flowers. The roots and seeds contain the harmful toxins, or alkaloids, that cause respiratory paralysis. Hemlock poison is fast-acting and usually brings death fairly quickly. Typical early-warning signs are excessive salivation, loose and frequent stools, muscle weakness and tremors, disorientation and coma.

3) Foxglove is more of a garden plant than one you might find in fields, however, it is not unheard of for foxglove to get harvested with hay, so always be vigilant. Foxglove is also thought to be more palatable when harvested and as little as 100g of it can prove fatal. The plant is poisonous to other animals beside horses and will also harm humans. It is characterised by brightly coloured, tubular flowers along a long, leafy stem.


4) Buttercups are commonly found in pastures and can cause mouth ulcers and blistering if consumed by grazing horses. In small quantities, buttercups aren’t too threatening but they can still cause stomach upsets and general discomfort. In their dried form i.e. when harvested in hay and haylage, buttercups are no longer harmful so you needn’t worry.

5) The berries and foliage of Deadly and Woody Nightshade are highly toxic yet both are described as naturally distasteful and are less commonly eaten by grazing horses. Nightshade is found in open fields and pastures, in wooded areas and in wild growth at the roadside. The plant is tall with purple, bell-shaped flowers and sweet, faintly scented berries.

Deadly Nightshade

Beside poisonous plants, there are also a number of hedges and trees that are toxic to horses when ingested. These should be fenced off or cut down to prevent accidental poisoning.

  • Oak
  • Yew
  • Laburnum
  • Laurel
  • Privet
  • Rhododendron
  • Sycamore seeds are linked to Equine Atypical Myopathy - a serious condition with a high mortality rate.

Hopefully you have found this article useful and if you have any thoughts on the discussion, please share them with us! Feel free to contact me directly with any further questions and/or suggestions for future blog posts: [email protected]

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2nd Apr 2015

very informative,

2nd Apr 2015
Customer Since: February 2015
From: Hants, United Kingdom

Sycamore seeds even when on the ground for a long while can still be just as toxic (as far a research has yet shown) So don't think they'l be ok now for your horse/pony to eat.
You need to pick up every last one on your grazing or hire a Billy Goat type field Vacuum to be sure your grazing is safe for you horse to eat and for you to sleep at night. We lost a hosre to sycamore posioning in Oct and it was an awful thing to see your horse collapse and die in front f you.When she was perfectly healthy 7 yr old.... R.I.P. Molly ( friends horse, same filed as mine)

3rd Apr 2015

a very useful, concise list to have and pass on to friends

4th Apr 2015

Does oak not depend on if it is the leaves or scorn and when one or the other is green or dried. Is bracken not also toxic either green or dried ?

7th Apr 2015

Thank you for all your comments and sorry to hear about your loss Diane.

Mil - It is the acorns from an oak tree which are poisonous and some horses can develop a taste for them! They can result in colic.

Bracken is also toxic, fresh or dried generally horses wont eat fresh bracken unless there is nothing else to eat.

9th Apr 2015

Horsetail is also poisonous. Destroys Vit B1 in the horse's body. Its worth google-ing this plant.

22nd Apr 2016
Customer Since: December 2012
From: Aberdeenshire, United Kingdom

Hi My comment is not about plants but I wonder if other people have every been bothered with crows my horse was being attacked I thought for her hair however they have been drawing blood my worry is what they leave behind I have had to put a rug on her to keep them off. Additionally they have killed several small lambs on the farm HELP !! what can I do

24th Feb 2018

Buttercups in haylage is NOT a guarantee that the toxic elements have dried and evaporated as haylage is NOT a DRY forage. It is baled when around 40-60% moisture.
If your horse or pony has any liver damage - and you feed haylage with buttercup in - AND he's white skinned, it IS possible for photosensitivity reaction to occur - and the 'build up' of the toxin in the system causing illness (because the liver isn't able to break buttercup toxins down due to damaged liver from ragwort or mycotoxins)
I would like it if someone in the world would test for buttercup toxin in haylage to put this issue to rest.
I read everywhere that buttercup in haylage is okay - yet my horse was very ill on it, and only recovered once the buttercup haylage was stopped. (There wasn't much buttercup in the haylage BTW) It was very good quality haylage!
So please be careful with buttercup in haylage - it's not wise to presume it's safe and disregard it as a possible toxic reaction you're horse may be showing.

26th Apr 2018

a really interesting report

26th Apr 2018
Customer Since: July 2015
From: Bedfordshire, United Kingdom

Very helpful and will be on the look out for the ragwort rosettes

26th Apr 2018
Customer Since: August 2013
From: Dorset, United Kingdom

My horse likes nothing better than young bracken shoots. I have to monitor the field every day when it starts to grow. He eats it, given the chance, even when there's loads of grass.

27th Apr 2018
Customer Since: June 2017
From: United Kingdom

Sycamore is the biggest problem I have. It's not even in my field; it's my neighbours & they also have horses.

27th Apr 2018
Customer Since: October 2014
From: Worcestershire, United Kingdom

Hi Hazel. I’ve not had an animal incurred by crows but a few years ago I had a terminally ill pony who used to spend a lot of time lying down. I was shocked to quite often see crows sitting on and walking around on him. They obviously knew they could get away with it. I remember listening to. Jeremy Vine phone in on problems with seagulls a couple of years ago attacking pets in gardens.

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