Poisonous Plants for Equines

Ragwort will appear in your pastures in the seedling stage from autumn to June. It is important to spot them at the rosette stage at about 10-15cm high.  

As the rosette develops, the leaves look irregular with jagged edges. Rosettes are often dark green but can be tinged with purple. 

As the plants grow, yellow daisy like flowers will appear from June to late October. 

One plant can produce and spread thousands of seeds which can lay dormant for years. The seeds ripen in July/August and are normally shed from September onwards.  

An adult plant can grow anywhere between 30-100cm depending on the environment.  

Ragwort is a deep-rooting plant. 

Ragwort is a common weed that can be seen on wasteland, road verges and river banks. 

As horse owners the concern is that ragwort can easily spread from neighbouring land. 

While ragwort is growing it tastes bitter to the horse so they usually will not eat it unless food is in short supply. When ragwort is wilted and dried it becomes much more palatable, loses its bitter taste. It will remain toxic, and care must be taken as it can be accidently found in hay. 

Clinical signs include:    

• The horse becomes depressed / lethargic 
• Jaundice (a yellow tinge in the gums and eyes) 
• Photosensitisation (inflammation of the skin) 
• Diarrhoea occurs 
• Abdominal pain (colic) 
• Weight loss 
• Neurological signs including head pressing, loss of coordination, continuous circling, seizures 
• Aggressiveness that is not normally present 

Impact on the horse if it has eaten ragwort: 

• Ragwort contains Pyrrolizidine Alkaloids (PAs), and ingestion leads to toxic by-products produced in the liver. 
• These toxic by-products called pyroles disrupt DNA function in the liver cells. 
• Damaged cells lose their capacity to regenerate. 
• The liver has the ability to function until approximately 70% becomes damaged. 
• At this stage there is no effective treatment to reverse the damage to the liver cells. 

Clinical signs of ragwort poisoning and toxicity: 

• Secondary photosensitisation: Inflammation of the pink skin, due to secondary liver damage (from the ragwort), different to primary photosensitisation, which is without liver damage from St. John’s Wort (another toxic plant).

• St John’s Wort:  Looks very similar to ragwort and can often be mistook for this due to similar clinical signs. The way to tell the difference between this and ragwort toxicity is through a blood test. St John’s Wort causes no liver insult/pathology on bloods and has slightly bigger flowers. 

Herbicide treatment 

• Horses must be removed from the pasture before the herbicide is applied to the land. 
• A risk assessment must be completed. 
• Some products require a qualified specialist to carry out the application. Details are available from the National Association of Agricultural Contractors.
• The herbicide should be applied when the ragwort is at the rosette stage in spring.
• Apply the herbicide on a mild, non-windy day, making sure the vegetation is dry and that rain is not expected for at least a few hours.
• The horses must only return when all the ragwort has fully disintegrated. This can take a several weeks, so follow the product specific guidelines carefully. Remember that dead ragwort is still toxic and palatable.

Improve pasture management 

• Ragwort thrives on poor quality pasture.
• Rosettes left alone will compete with surrounding plants.
• Improving your pasture quality will help reduce the opportunity for ragwort to grow.

Hand pulling or using a ragwort fork  

• Always wear gloves. 
• This is suitable for a smaller area of land.
• Make sure the whole of the root is removed, as any fragments of the root left within the soil will result in the ragwort regrowing.
• It is easier to pull the ragwort, including all of the roots when the soil is damp.
• Ragwort-specific tools are available to help with successful root removal.

What do you do with the ragwort when removed? 

• Consider how you will dispose of ragwort at the same time as planning a control system.
• Where possible, use on-site disposal.
• If there is any risk of seeds being dispersed, the flower heads can be cut off and placed in sealed bags. 
• When handling ragwort (either live or dead plants) gloves must be worn, and a facemask is recommended to prevent the inhalation of ragwort pollen.

Controlled burning 

• Ragwort should be stored under cover to wilt or in paper bags where horses cannot access it. 
• Ragwort burning or incineration must be undertaken and supervised by the owner/occupier/manager of the premises. 
• You must check with your local authority for any bylaws prohibiting burning of garden waste.

Rotting down 

• Ragwort can rot down well on site if away from horses.
• If you have a large amount of pulled ragwort you may need to contact a waste management company so it can be professionally removed.

What you must not do….

• Bury ragwort in manure heaps 
• Use ragwort as animal bedding 
• Dig, bury or plough ragwort into the ground 
• Attempt to dry ragwort where animals could access it 
• Allow seed dispersal from plants awaiting disposal 
• Transport ragwort unnecessarily 
• Transport ragwort unless it is in sealed bags or containers 

Mowing/cutting

• It is not advised to mow or cut ragwort as the roots will still be in place and the plant will grow again.

Foxglove can grow up to 2 metres in height. The flowers appear from June to September. Mainly found in hedge rows and the edge of woodland. Ingesting as little as 100 grams of this plant can be fatal, and while foxglove in wet soil aren’t very appetizing to equines, it’s highly dangerous when dried in hay.

 Clinical signs of Foxglove Poisoning and Toxicity 

• Contains cardiac glycoside toxins.   

Clinical signs include:  

• The horse will experience changes to heart rate and breathing difficulties. 
• Diarrhoea will be present. 
• Pupils will be dilated and the horse will experience tremors and fits.

Prognosis and treatment: 

• Foxglove poisoning can cause death in just a few hours.
• You should contact your vet as soon as possible if you think your horse has eaten. foxgloves. And the sooner the better, a vet may use activated charcoal and mineral oil to flush out the toxins if caught early enough.
• The sooner the better, a vet may use activated charcoal and mineral oil to flush out the toxins if caught early enough.
• There are few treatment options available, unfortunately the toxins can act immediately on the horse’s cardiovascular system, causing damage.

Prevention 

• Prevention is better than cure.
• Horses do not usually eat foxgloves when on good pasture. They will normally only eat it when no other food is available.
• Keep horses away from areas of foxglove growth.
• Remove any foxgloves on your land as soon as you see it. Just like ragwort the plant remains toxic when the plant is dried and dead.

Deadly Nightshade can grow up to 1.5 metres in height. The leaves can grow up to 20cm long. The flowers are most often a dull brown-purple colour and grow up to 3cm.The berry is black and shiny. 

Clinical signs of deadly nightshade poisoning and toxicity 

• In all parts of the plant, including the stems and leaves the toxin is atropine alkaloids. 

Clinical signs include:    

• Pupils will be dilated, and blindness will occur.  
• Heartbeat will change.  
• Muscle tremors will occur. 
• The horse will experience disorientation.  

Prognosis and treatment: 

• If you think your horse has eaten deadly nightshade, call your vet and follow the advice. 
• Death from deadly nightshade intoxication is rare.  

Prevention 

• Remove any deadly nightshade in your pasture by pulling or digging it up. 
• Horses find deadly nightshade unpleasant therefore rarely eat it.  

Ivy has dark green, triangle shaped leaves. It grows in vines.

Clinical signs of ivy poisoning and toxicity: 

• Toxins in ivy are triterpenoid saponins and polyacetylene.  

Clinical signs include:    

• The horse will have diarrhoea
• Colic may occur
• Signs of skin irritation around the mouth  
• The horse will have a loss of appetite   
• Dehydration will occur 

Prognosis and treatment: 

• Contact your vet as soon as you think your horse has eaten ivy to treat the symptoms and prevent any further toxin damage.
• Death from ivy poisoning is rare.

Prevention: 

• Remove any ivy you find in your pasture.
• Ivy is unpleasant to horses so they will rarely eat it.
• Keep horses away from areas where ivy grows.   

Yew are evergreen trees or bushes and can grow up to 20 meters high. The thick trunk is a red-brown colour with scaly and peeling bark. Leaves are around 1-3cm long and dark green, needle shaped. The young leaves are bright green, and the berries are red. 

Clinical signs of yew poisoning and toxicity: 

Yew contains the deadly toxin taxine, a cardiotoxin that causes a heart attack.

Clinical signs include:    

• Sometimes the only sign given is sudden collapse of the horse.   
• Groaning sounds may start with the horses breathing.  
• The horse will experience muscle tremors and disorientation.  

Prognosis and treatment: 

• Contact your vet immediately if you think that your horse has eaten yew.
• Taxine poisoning can be fatal.

Prevention 

• Offer plenty of forage to horses as they do not normally eat yew due to its bitterness. If food is in short supply, they may be forced to eat it.
• Keep your horse well away from any yew plants. Put up a fence to keep horses away from any yew hedges on neighbouring properties.
• Dead yew and clippings still contain toxins.

Laburnum can grow to 8 metres high. The bark is a smooth, grey or olive – green colour. It produces bright yellow flowers that droop.  

Clinical signs of laburnum poisoning and toxicity: 

Laburnum contains the toxin cytosine, it is present in all parts of the plant, but especially the seeds. 

 Clinical signs include:    

• The horse will experience colic and diarrhoea.  
• Signs of drowsiness, excessive salivation, fitting, collapse and coma. 

Prognosis and treatment: 

• If you think that your horse has eaten laburnum, contact your vet immediately. 
• Your vet may use activated charcoal and fluids to flush the toxin out.  

Prevention: 

• Laburnum tastes bitter to horses so do not normally eat it unless short of food.  
• Keep your horses away from areas where laburnum trees grow or fence off the area around the trees to avoid horses reaching it.