Poisonous Plants

December 2020

The list of poisonous plants, shrubs, hedges and trees is extensive and horse owners should make themselves aware of what is unsafe for their horses. Poisonous plants often thrive on poor quality land, making it even more important to maintain good pasture. Regularly check for and remove poisonous plants if they are found. It’s advisable to wear gloves when handling poisonous plants.

Do you have ragwort on your pasture? Visit our Ragwort Toolkit for further details on how to identify and safely and effectively remove ragwort.

There are a number of trees known to be poisonous to horses such as sycamore, yew and oak. The largest proportion of concerns the BHS see from horse owners each year are regarding Atypical Myopathy and Acorn poisoning. Further information can be found below:

 

 

Plant / Shrub Species - Identifying Clinical Signs Treatment Prevention

Foxglove

Foxglove

 - Can grow up to 2 meters tall

 - Flowers are purplish-pink, hanging, tubular structures which are 4-5 cm long and appear from June to September.

Foxglove contains cardiac glycoside toxins1.

Cardiovascular signs
of poisoning include changes to heart rate and breathing difficulties.

  Digestive signs include diarrhoea.

Neurological signs
include dilated pupils, tremors and fits. Death from foxglove poisoning can occur after just a few hours1.
Treatment options are limited as the toxins can immediately damage a horse’s cardiovascular system.

 Contact your vet as soon as you suspect foxglove poisoning.

If caught early enough, activated charcoal and mineral oil may be used to flush out the toxins1.
Horses will not usually consume foxglove when other food is available. Horses should be kept away from areas of foxglove growth and any found on your pasture should be removed immediately.

 It is important to note that toxicity remains even when the plant is dried and dead1.

Deadly Nightshade

Deadly Nightshade

- Grow up to 1.5 meters high
              
 - Leaves can grow up to 20cm long

 - The flowers grow up to 3cm long and are most commonly a dull brownish-purple colour

 - The fruit is a shining blackberry.

Ingestion of the plant releases atropine alkaloids into the body1.

Clinical signs include:
 - Dilated pupils and blindness, changes to heartbeat, muscle tremors, disorientation.
Death from deadly nightshade intoxication is rare but a vet should always be called for supportive treatment. Deadly nightshade is rarely eaten as it is distasteful to horses.

Any deadly nightshade found should be removed by pulling or digging up.

 All parts of the plant are toxic, especially stems and leaves1.

Ivy

 Ivy

- Leaves are dark green and often in the shape of a triangle
 
- Grows in vines.

The toxins within ivy that harms horses is triterpenoid saponins and polyacetylene.

 Symptoms of ivy poisoning may include diarrhoea, colic, skin irritation around the mouth, loss of appetite, dehydration.
Death from ivy poisoning is rare.

  If you suspect your horse has eaten ivy your vet should be contacted immediately to treat the symptoms and prevent any further toxin damage.
Ivy is rarely eaten as it is distasteful to horses.

Horses should be kept away from areas where ivy grows, and any ivy found should be removed

 

 

Tree Species - Identifying Clinical signs Treatment Prevention

Yew


Yew
 
-Evergreen trees or bushes can grow up to 20 meters high

 - The trunk is thick with reddish brown, scaly, peeling bark

 - Leaves are typically 1-3 cm long. Young leaves are bright green and darken as they mature

 - Red berries also often found.
Yew contains the deadly toxin Taxine.

Neurological signs may include muscular trembling and uncoordinated movements1.

Animals may collapse and breathing may begin to sound like groaning.

Sudden collapse is sometimes the only sign.
Death by taxine poisoning can occur instantly.

Taxine is a cardiotoxin causing a heart attack1.

A vet should be contacted as soon as possible.
Yew is bitter tasting and horses will not usually eat it unless other forage is short, especially in winter.

Ensure the horse is kept well away from any yew plants.

Be aware that toxicity remains in clippings and dead plants1.

Laburnum

Laburnum
 
- Laburnum trees usually grow to 7-8 meters

 - Tree is covered with smooth grey or olive-green bark

 - Laburnum produces bright yellow plants arranged in drooping flowers.
Laburnum contains the toxin Cytisine, which is present in all parts of the plant, but especially the seeds2.

Digestive signs of poisoning include colic and diarrhoea.

Neurological signs can include drowsiness, excessive salivation, fitting, collapse and coma2.
If poisoning is suspected, contact your vet immediately for supportive treatment.

They may use activated charcoal, liquid paraffin and fluids to flush the toxin out2.
Horses will not usually consume laburnum due to its bitter taste; however, horses should be kept off areas where the trees grow or fence off the area around Laburnum trees to avoid access to it.

 

Resources

1) Cheltenham Equine Vets. 2018. Plants Poisonous to Horses. Available from: https://cheltenhamequinevets.co.uk/wp-content/uploads/2018/02/Plants-poisonous-to-horses.pdf

2) Simon Constable’s Equine Vets. Laburnum Poisoning. Available from: https://equine-vets.com/health/l/laburnum-poisoning/

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