Regular followers will know that, on the basis of detailed study of the evidence, we know that ragwort poisoning of horses, cattle etc. is rare. Or to qualify that all the reliable figures that are available say it is rare. The figures around saying the contrary have no proper basis. To properly determine if ragwort causes poisoning you need to do a post mortem.
They will also know that the press, the internet etc. are full of people panicking wildly. If they so much as touch it will kill people, horses, cattle, your pet cats and dogs and even tortoises. It is nonsense of course.
If you go into any of the forums and someone starts talking about any kind of sickness with a horse, someone else will very often suggest ragwort is to blame.
If an expert goes into the forum they get shouted down and abused. Like this example of Esther Hegt the noted expert from the Netherlands.
Well the latest one made me laugh. There is now panic over emus!
OK perhaps I shouldn't laugh. Someone is only trying to be helpful and they have I have been told lost their precious much loved pets. People loosing their animal companions is no joke, but the hysteria around ragwort is.
I should also explain that people being hurt is part of my motivation for writing this blog. It isn't just ecology. People are being ripped off by people collecting money or selling dodgy cures and treatments. There is also the serious potential problem of vets getting things wrong, and there are more examples than those which I have at present written about. This leads to more animal suffering through misdiagnosis. It also makes people panic and worry about their pets when there is no need. This is harmful. The hysteria needs to be exposed for the laughable nonsense that it is.
A rather sensibly sceptical person has asked how much ragwort would kill an emu?
It seems a friend is blaming a bit of ragwort that has fallen into a water trough for killing emus. It is extremely unlikely that ragwort is the cause. I don't know how often vets do this and therefore how much information is likely to be available for comparison but the answer is to do a post mortem on the emus.
There is no simple answer to the question. I cannot find any example in the literature of an emu being poisoned by ragwort. The alkaloids in ragwort are extremely common, however since they occur in 3% of all plants. (We never hear panic about the others.) We so find, therefore, that there are records of birds being poisoned by contaminated feed from other plants.
However, we come back to the basic point. Animals of all kinds are exposed to these substances in a variety of plants and it always takes quite a bit to poison for a variety of reasons related to the way in which this works. We know from the biochemistry that a lot of the alkaloids react in ways that cause no harm so small doses will have no effect.