Poisonous plants horses should avoid

The most common poisonous plants in the UK are ragwort, foxglove, nightshade (deadly and woody), hemlock and buttercups. Poisonous trees also include yew, sycamore, oak and laburnum, and hedges, privet, laurel and rhododendron.

It’s important you know how to recognise them, maintain good pasture management and know the signs of poisoning in horses and ponies.

Foxglove

Foxglove grows across the UK. Horses will not normally eat fresh foxglove, but it's more palatable in hay and just 100g could prove fatal. 

Symptoms of foxglove poisoning include:

• contracted pupils
• drooling
• vomiting and diarrhoea
• breathing difficulties
• convulsions or seizures

If you spot any of these symptoms contact your vet immediately. Treatment is limited, so ensure foxglove is removed in fields.

Deadly nightshade

Poisoning from nightshade is not normally fatal in horses, despite it's name, but a vet should still be contacted. Symptoms of poisoning can include:

• dilated pupils
• muscle tremors, convulsions or seizures
• loss of consciousness

Buttercups

Buttercups are bitter and, in most cases, will be avoided by horses. Dried buttercups are harmless in hay, but fresh buttercups are poisonous in very large amounts.

Some common symptoms of poisoning include:

• drooling and excess saliva
• blisters in their mouth
• diarrhoea

Seek professional advice on spraying to remove from grazing areas.

Hemlock

Horses will not tend to graze on hemlock unless they have no other choice, but it can be toxic and fatal. Water dropwort and cowbane from the same family as hemlock can also be fatal. Symptoms include:

• dilated pupils
• lack of coordination
• tremors or seizures
• loss of appetite
• drooling
• bloating
• stomach problems and more frequent bowel movements

Common poisonous trees to horses in the UK

Sycamore, maple and other acers

Sycamore (helicopter) seeds and seedlings contain hypoglycin-A which is lethal to horses, causing atypical myopathy. Seeds can travel significant distances in the wind. 

Be extra vigilant in spring and autumn, remove any sycamore seeds or seedlings you see, fence off the area and consider felling the tree if you can. If you do choose to remove a tree, consider replacing it with a native, non-poisonous species to provide shade and reduce the impact on the environment.

Symptoms of sycamore poisoning include:

• sweating
• depression or changes in behaviour
• muscle stiffness or tremors
• reluctance to walk, weakness or difficulty standing
• breathing difficulties
• dark urine (reddish in colour)
• collapse

Contact your vet immediately if you see any signs or there is evidence your horse may have eaten sycamore seeds.

Oak trees and acorns

The plant, blossom and fruit are all dangerous to horses, but acorns pose the highest risk as many horses find them tasty. They can lead to severe colic and poisoning if eaten in large quantities.

Symptoms of acorn poisoning include:

• depression or changes in behaviour
• stomach problems or pain
• loss of appetite
• changes in bowel movements or diarrhoea

Oak trees drop their acorns in the autumn. Check for and remove acorns, provide plenty of other grazing, and move horses away from any falling acorns in autumn.

Yew

Yew is common tree or hedge in gardens and the plant, fallen leaves and berries are all lethal to your horse. It has a bitter taste, but horses may eat it if there's a lack of other grazing.

Symptoms of yew poisoning include:

• muscle tremors
• lack of coordination
• collapse

Be careful of fallen leaves and berries being blown into your field, even if the hedges are fenced off. Just 500g can be fatal. Contact your vet straight away if you are worried your horse might have eaten yew.

Laburnum

All parts of the laburnum tree are toxic, but the seeds have the highest concentration of poisonous cytisine. Horses will not tend to eat laburnum and it does not often grow in pastures, but it can be common in nearby gardens.

Symptoms of poisoning include:

• colic and diarrhoea
•  depression or change in behaviour
• drowsiness
• drooling
• seizures

Broom and lupin plants also come from the same family and can be fatal if eaten by horses.

Common poisonous shrubs to horses in the UK

Many poisonous shrubs will not be common in most paddocks, but you'll need to be careful if any fields back onto gardens.

Privet

Privet is common in gardens so be careful of neighbours' hedges and the possibility of people dumping cuttings in the field.

Symptoms include:

• stomach problems and diarrhoea
• lack of coordination
• collapse
• paralysis

Box privet is the most dangerous, as eating even small quantities can kill a horse.

Rhododendron (azaleas) and laurel

Horses will often eat other plants over these shrubs if given the choice. Symptoms of rhododendron poisoning include:

• weakness
• drooling
• stomach problems and more frequent bowel movements
• paralysis

Very small quantities of this plant are highly toxic to horses, affect their breathing (respiratory system) and can lead to death.

Bracken ferns

Bracken can be dangerous if it becomes a regular part of a horses diet. Symptoms can include:

• weight loss
• muscle tremors
• difficulty walking or standing
• seizures

Speak to your vet about treatment if you're worried about your horse.

How to avoid and get rid of poisonous plants

Good pasture management is crucial to caring for your horses:

• Uproot poisonous plants before they go to seed, wearing protective equipment if needed. Remove them from the field and burn them. Some hazardous plants, like buttercups, may only be eradicated by spraying with a suitable weed killer.
• Spot spray small areas and individual plants. The best time to do this is when the plants are still young. Remember to keep horses from grazing this area until after the recommended time. 
• If you can, we recommend felling any poisonous trees
• Keep poisonous trees and hedges fenced off and cut well back to prevent horses reaching them over the fence. Fence off ornamental plants, trees and shrubs if in doubt as many are likely to be poisonous.
• Collect or fence off sycamore seedlings and seeds and acorns in autumn to prevent ingestion
• If your paddocks back onto gardens, check that none of these are growing over into grazing areas. Make sure that kind-hearted gardeners are not giving prunings to your horses to eat!
• Many plant poisons are cumulative, so if your horse eats them with no ill side effects it shouldn’t mean you should continue to let it eat them

Signs of plant poisoning in horses

There are a variety of symptoms you might see if your horse has eaten something toxic. If your horse experiences any of the following signs, you should speak to your vet:

• weight loss
• tiredness, lethargy or difficulty standing
• sweating
• muscular stiffness
• dark urine or blood in their urine
• changes in bowel movements
• colic
• fluid accumulation in the legs (edema)
• breathing difficulties
• tremors or seizures