Myths about the number of casualties due to Ragwort poisoning.
In order to assess the impact and scale of the Ragwort problem, it is important to find out how many animals per year become victims of Ragwort poisoning. Because only a post mortem can show if an animal has died from Ragwort poisoning, and this is only rarely performed. Read more
Ragwort poisoning: one bite doesn’t hurt?
Common ragwort and all other ragworts and groundsels growing in the Netherlands contain compounds that are poisonous to most vertebrates and insects. These secondary metabolites are called pyrrolizidine alkaloids (PAs). In plants, these substances are stored in their non-toxic form, but after the plant has been eaten, chemical processes in the intestines and liver transfer these PAs into a toxic form that can damage the liver and, to a lesser extent, also other organs such as kidneys and lungs. In contrast to what is commonly thought, PA's don’t accumulate in an animal’s body. In fact, they are usually excreted in about 24 to 48 hours (please see our separate webpage for more information on pyrrolizidine alkaloids and their metabolism). Read more
Is it true that horses usually do not eat fresh Ragwort?
All Ragworts (Tribe Senecioneae, Family Asteraceae) growing in the Netherlands contain pyrrolizidine alkaloids of the senecionine type. These substances are toxic for most vertebrate animals and insects. If a horse eats it fresh or dried, poisoning will occur. Research shows that Ragwort plants when dried, remain toxic for a very long time. Horses don't recognize dried Ragwort plants as poisonous and hay which contains Ragwort can thus cause Ragwort poisoning. Ragwort plants are sometimes part of the flora of an area where horses are kept, and the horses will have the opportunity to eat ragwort fresh. If and to what extent this happens, is not quite clear. Read more
Ragwort poisoning through skin absorption. Fact or Fiction?
Several websites and other media report that the poisons in ragwort (pyrrolizidine alkaloids) can be absorbed through the skin and therefore all skin contact with ragwort plants should be avoided. To find out if this information is accurate we went looking for the original source of this information. Up until now we have been able to trace these reports to two sources. Read more
Many seeds, many plants?
On the internet and in other media people express their concern that Common ragwort is becoming more common in the Netherlands and that this species will soon be present in more and more areas where it was previously absent. In addition to this, there is a call for fighting Common ragwort not only in horse fields and their direct vicinity, but also in areas that are more remote, because the wind dispersed seeds can travel large distances and can therefore still end up in areas where horses graze. In this context, it is often mentioned that a Common ragwort plant can produce up to 200.000 seeds and that these can be dispersed many miles away from the mother plant. In order to improve our understanding of the factors that contribute to the dispersal of Common ragwort seeds, Read more