Ragwort poisoning is one of the most common forms of poisoning in horses. It causes irreversible liver damage and digestive disorders.
The effects on the liver are cumulative and because a horse only uses a proportion of his liver, he can withstand some damage without any symptoms showing at all.
When damage reaches a certain level (which could follow years of eating a small amount of ragwort or just days of gorging on the plant), the poisoning will lead to death.
One of the difficulties with ragwort poisoning is that the symptoms don’t show until it is too late.
Rosette stage: Most people only realise they’ve got ragwort when it flowers. But the easiest and most effective time to rid your fields of the weed is when it is 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.
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.
Flowering and seeding: Ragwort flowers from July to September. The bright yellow daisy-like flowers are densely packed together in flat-topped heads.
If left togrow unhindered, the stems of mature plants become woody and tough and can reach up to 1m (3ft 3in) in height.
Clusters of downy seeds, resembling small dandelion seedheads, soon replace the flowers and this is where the problem gets out of hand.
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 the soil for 20 years.
- Ragwort is most common in areas of poor pasture.
- Dead, dry ragwort is more palatable than the live plant, and even more toxic.
- Many cases of ragwort poisoning are caused by horses ingesting dried ragwort in hay. However good your hay is, don’t assume it is free of ragwort – check it regularly.
- Some environmentalists fear that the eradication of ragwort may threaten the survival of the Cinnabar moth (its caterpillar young feed on the weed). But the moth can also feed on Groundsel, so this worry is without foundation.
- As well as common ragwort, there are other types: Oxford, marsh and hoary.