Tansy Ragwort Poisoning in Horses

Tansy Ragwort Poisoning in Horses - Symptoms, Causes, Diagnosis, Treatment, Recovery, Management, Cost
Tansy Ragwort Poisoning in Horses - Symptoms, Causes, Diagnosis, Treatment, Recovery, Management, Cost

What is Tansy Ragwort Poisoning?

The effects of your horse eating tansy ragwort are not always clear at first as the effects are slow to develop. It begins with your horse acting lethargic, and showing aversion to the sun, followed by blindness and respiratory difficulties. Then a total shutdown of the liver occurs in the worst hit cases. Ragwort is toxic to your horse, even if it is dead, so careful removal of the whole plant and roots is vital. It can affect humans so be careful when removing the plant and protect yourself from breathing in any pollen.

Tansy ragwort is a poisonous plant for horses, often not showing its effects until it is too late, with liver failure the ultimate result.

Symptoms of Tansy Ragwort Poisoning in Horses

  • Weakness and lethargy
  • Difficulty standing
  • Walking in circles
  • Staggering 
  • Yellow mucous membranes or jaundice 
  • Head pressing against a wall or fence
  • Weight loss through lack of appetite 
  • Dull coat 
  • High fever
  • Restlessness
  • Photosensitisation  
  • Liver failure 
  • Loss of sight 


  • Tansy ragwort is a toxic weed that originates from Europe and is similar to common tansy which is regarded as a less consumed plant due to its strong odor and very bitter taste; tansy ragwort has an outer ring of petals on its blooms
  • Common tansy has the really strong odor and bitter taste but has a button like bloom to its shape, with no outer ring of petals like the ragwort variety
  • Both are toxic and considered to be a pest


Causes of Tansy Ragwort Poisoning in Horses

  • Although bitter to taste, if your horse is not getting enough feed, or lack of feed due to overstocking the pasture, your horse may resort to eating ragwort to combat hunger 
  • Ragwort is more palatable once it mixes in with hay or dried grass 
  • Dead ragwort retains its toxicity, so remove all traces carefully 
  • Poor pasture management can cause toxic poisoning


Diagnosis of Tansy Ragwort Poisoning in Horses

Sadly, once the signs of the disease are evident, it is typically too late to help your horse. By the time the above symptoms appear, the liver is usually suffering as the cells die off leaving the liver compromised and unable to function. Prevention and careful observation is by far the prudent way to manage the spread of this toxic plant. Some animals may survive for several months after ingesting tansy ragwort, but others may not last very long at all depending on the amount eaten. Although the plant has an unpleasant smell and taste, a hungry horse may nibble on it to try and fill its belly. Even if your horse doesn’t eat it, if the pasture is infested parts of the plant may break off and die, mixing in with dried grasses so that your horse doesn’t notice them. This plant is hard to get rid of completely, needing careful removal to ensure the roots are taken out completely and before seeding occurs. Even the best pasture management cannot be considered safe as seeds lying dormant in the ground can germinate a few seasons later and start the cycle again.

If you discover that your horse may have been ingesting tansy ragwort, contact the veterinarian for an evaluation of your equine’s health condition. If caught early enough, blood tests may reveal a toxicity, with relevant markers pointing to liver damage. A liver biopsy is also a good indicator of the poisoning.



Treatment of Tansy Ragwort Poisoning in Horses

There are no vaccines, medicines or surgery available that can help if your horse has eaten a lethal amount of this noxious plant. By the time the symptoms alert you or your veterinarian to the problem and your horse’s condition is diagnosed, your horse’s liver will be disintegrating leading to a slow demise. Out of kindness for your horse, euthanasia is often the only option. This disease or toxicity develops insidiously – your horse may show no signs at all of any illness at first. But the toxin works its way into the liver and starts to destroy valuable cells and preventing the liver from repairing itself. Finally, by the time the symptoms show, the liver has been compromised past the point of recovery. This is the danger from this somewhat pretty but lethal plant. Aggressive pasture management to rid the property of this pest is vital, but even then, if the neighbouring property doesn’t do their part and rid their property, you will find it coming back again as seeds from the neighbour catches a ride on the breeze to infects your pasture.

If ingestion of the plant, whether it be in the pasture or mixed in with the hay is determined early enough, removal of the tansy ragwort from your horse’s proximity and prompt veterinary care may allow for improvement in your equine’s condition. The liver is able to repair itself if the damage has not progressed beyond repair. Your veterinarian can advise you on dietary changes and supplements that may encourage liver rejuvenation.



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Recovery of Tansy Ragwort Poisoning in Horses

As stated previously, prevention is by far the best course of action. Ensure your young horse is in a pasture where there is no ragwort, as young animals will often experiment eating unusual plants. Observation and regular pasture checking for the development of this noxious weed is vital. Contamination of hay and silage should be avoided at all costs. There are herbicides that can kill the plant, but just spraying alone is not enough. As dead ragwort is just as lethal, total removal of plant, root and parts of the dead plant should be stringently removed. The best time to spray is when the tansy ragwort is in the rosette stage. As always, take care when handling these herbicides.



Tansy Ragwort Poisoning Questions and Advice from Veterinary Professionals

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