The Dangers of Ragwort

Horse owners should know about the dangers of ragwort to their horse. Find out how to recognise it and the signs of ragwort poisoning

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Horse owners should be aware of the dangers of ragwort to their horse.  It is easiest to dig up at this time of year when the plants are small.

Liver disease and the dangers of ragwort:

Ragwort contains pyrrolizidine alkaloids. When a horse eats ragwort these are absorbed into the blood stream.  They are broken down in the liver to produce toxic agents that damage liver cells. These damaged liver cells then die and are replaced by fibrous tissue.  As more and more cells are damaged the liver shrinks and eventually there are not enough functional liver cells left to carry out the essential functions of the liver, and liver failure occurs.

  • Liver failure only occurs when over 75% of the liver has been damaged.
  • Signs of liver disease caused by ragwort poisoning can be mild, vague, or even absent. Serious signs often only become apparent when liver failure has occurred.
  • Diagnosis of liver disease is by blood tests. These will show if there is ongoing damage and if there is reduced liver function.
  • When liver failure has occurred treatment is very difficult and it is often fatal. This is why eliminating ragwort is so important.

Ragwort facts:

  • All parts of the ragwort plant are poisonous all year round.
  • Each plant can have up to 1,500 seeds which are carried in the air to infest new sites. These seeds can lay dormant in soil for 20 years.
  • Most animals will avoid eating ragwort as the live plant has a bitter taste, however it is thought that some horses can develop an acquired taste for the plant, especially if there is little else to eat.
  • When cut or wilted ragwort loses its bitter taste and becomes more palatable to horses. Drying does not destroy the toxins, so hay and haylage can be sources of ragwort poisoning.  Hay should be checked regularly for ragwort, once removed the rest of the hay will be safe to feed.
  • Eating a small amount of ragwort over a long period of time can be just as damaging as eating as eating one large amount.
  • Rubber gloves should be worn when handling ragwort as the plant is also potentially harmful to humans.

Recognising ragwort

Ragwort LeavesRosette stage:

Over the winter months and through to July, look out for dark green dense rosettes of ragged leaves which grow close to the ground before shooting up and thickening out.  This is the easiest and most effective time to rid your fields of the weed when it’s in its early stages – herbicides will work faster, digging up is less laborious and, because you haven’t allowed it to seed, you should have less of a problem next year.

Ragwort FlowersFlowering and seeding:

Ragwort flowers from July to September. The bright yellow daisy-like flowers are densely packed together in flat-topped heads.  Clusters of downy seeds, resembling small dandelion seed heads, soon replace the flowers and this is where the problem gets out of hand.

If you need any further information about ragwort or liver disease please contact a member of the equine team.

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