It is often claimed that ragwort kills thousands of animals a year. Whilst no one knows the exact figure all the evidence shows that this is not true.
There is published evidence to show this there are .UK government statistics for the year 2005 show for horse only a total number of thirteen deaths and in cattle there is a a French study that shows only eighteen suspected cases which occurred over a period of around a decade. Of this group only six were actually confirmed to be caused ragwort. There is also a set of statistics from a UK Government study covering a period in the 1980s and 1990s. This shows numbers in cattle in the 10-20 or so deaths a year range.
Why then is the claim of large number of deaths made? A scare story makes a good story. There has been a campaign against ragwort. Those involved often either stand to gain financially from the scare stories or are people who are not well versed in how to spot pseudoscience and hoaxes. There most interesting of the poor statistics that are often promoted is is a much publicised claim as the result of survey which was sent sent to members of the British Equestrian Veterinary Association.
Only a tiny percentage of the people actually contacted replied to this only four per cent in fact. The figures contained suspected cases. Then there was an extremely bad statistical treatment of the statistics obtained by extrapolating them as if all the people questioned had replied. They then claimed that 6,500 cases a year occurred.
This is dreadfully bad science as it is very poor practice and dangerous to extrapolate a small sample. It is obviously the case that a vet has a higher likelihood of responding is more likely to respond to a survey if they had actually dealt with cases of Ragwort poisoning . There are a whole set of statistical flaws in this survey, for example there was no attempt to remove duplicated reporting of cases and as a result is of no use whatsoever in in deciding the the truth Indeed the design and it seems that it may have been designed with the intention of giving a falsely inflated figure.
This ridiculously high figure has been much promoted by some horsey organisations and was a major element in a number of complaints we made to the Advertising Standards Authority.. It was publicised a great deal by the British Horse Society and repeated by companies who then had to withdraw the claim. Our specific complaint about a joint BHS leaflet was actually about misleading information about the law.
Unfortunately it has been allowed to influence government policy. It is interesting to note that in the Republic of Ireland where the UK anti-ragwort campaign has not run the following statement was made on June 5th 2005 by the Irish Minister for Agriculture and Food," "There are no official figures available in Ireland for deaths of horses due to ragwort poisoning. Unofficial estimates indicate that the level is very low and does not warrant any special attention or investigation."