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Pontifications on Poison

Being some ramblings on events associated with poisonous plants.

Tuesday 11th October 2011

I’ve had a response to my Freedom of Information requests to the University of Liverpool concerning the number of horses treated for liver disease at its Philip Leverhulme Equine Hospital where Prof Derek C Knottenbelt, BVM&S, DVM&S, DipECEIM, MRCVS RCVS is the European Specialist in Equine Internal Medicine. Professor Knottenbelt is a vocal campaigner against Jacobaea vulgaris, common ragwort, and his statements on the extent of ragwort poisoning are often repeated by those who seek its eradication.

Jacobaea vulgaris, common ragwort

Jacobaea vulgaris, common ragwort

I’m very pleased to find the response was inside the time limit (alright it was only two days inside but, still, that counts as a proper response), it gives quite a bit of the information I requested and offers a clear explanation of why not all of the information could be provided. With the information now received I can return to the subject of the 6th September’s blog. Usually, when I refer to a previous blog I just leave the link for people to follow but, today, I’m going to quote from that blog because it puts the information I now have into better context.

I’ll start by going back to the letter in the Yorkshire Post that started my enquiries. In it Professor Knottenbelt said of Jacobaea vulgaris, common ragwort, ‘…horses that die as result of the poisoning die in an appalling manner with unbelievable suffering…In my own clinic it is more than 10 per year…’ He gave this detail to justify his statement in the previous paragraph ‘…I have always erred on the side of caution when calculating the figures but for sure it is not less than 1,000 horses per year in the UK’. He then went on to say that the discredited claim from the British Horse Society that 6,000 horses die each year ‘is possibly high or possibly not’.

What followed is best quoted from the 6th September blog.

' I emailed to ask him;

‘‘Would you be kind enough to provide me with the actual number of deaths due to liver failure in each of the last five years?
‘‘Would you also tell me how many of those deaths due to liver failure were the result of pyrrolizidine alkaloid poisoning?
‘‘Of those, how many were proved to be the result of the ingestion of Jacobaea vulgaris, common ragwort?
‘‘And, in those cases, was the route of administration of the poisons determined and, if so, what were the routes found?’
‘The professor was kind enough to answer very quickly but, unfortunately, he wasn’t able to answer any of these questions. He said that the ‘more than 10’ was a ‘rough guide’ but went on to state that this was an underestimate.’

Here is exactly the reply to my first two questions from the Professor’s email which he interspersed with my questions;

‘You state that, in your clinic, you see ‘more than 10’ deaths each year due to poisoning.
‘The rough guide of 10 is an underestimate since I know the vehement defence of RW is almost paranoia now!  We have a variable number from year to year and I would have to look that up.  
‘Would you be kind enough to provide me with the actual number of deaths due to liver failure in each of the last five years?
‘See above  - I am not that bothered about retrieving the stats and I am retired anyway so its [sic] not up to me to fight this battle any more.’

It was this reply that decided me to make a Freedom of Information request to the University of Liverpool asking similar questions but couched more precisely as I’ve found in the past that some people try and exploit poor drafting of an FOI request to obfuscate. I also asked an additional question about Professor Knottenbelt’s status since the university website said he had come out of retirement.

The university’s reply repeated my questions before giving a tabular response. This is directly copied from its email;

'Q1. For each of the years 2006 to 2010, please provide the following information for the Philip Leverhulme Equine Hospital;
1.       The number of horses treated for all and any form of liver disease
2.       The number of cases in which poisoning was suspected
3.       The number of cases in which poisoning was evidentially established
4.       The number of horses that died of liver disease
5.       The number of horses euthanized because of untreatable liver disease.

  2006 2007 2008 2009 2010
Q 1.1 2 3 1 6 6
Q 1.2 2 1 0 1 2
Q 1.3 N/A N/A N/A N/A N/A
Q 1.4 N/A N/A N/A N/A N/A
Q 1.5 N/A N/A N/A N/A 2

So, on the key question of number of horses treated for liver disease the total for five years is only 18 and the number suspected of suffering poisoning totals 6. It’s hard to see where Professor Knottenbelt’s ‘more than 10’ deaths per year from ragwort poisoning are coming from if only 1 or 2 horses are being treated each year for poisoning of any sort.

I asked my second question in four parts, again to try and ensure it was completely clear. This was the response;

‘Q2.Would you also please advise the status of Professor Derek Knottenbelt on the 6th September 2011. Was he;
a.       An employee of the University of Liverpool and/or the Philip Leverhulme Equine Hospital
b.       A consultant to the University of Liverpool and/or the Philip Leverhulme Equine Hospital
c.       A volunteer offering unpaid services to the University of Liverpool and/or the Philip Leverhulme Equine Hospital
d.       Retired from his previous role with the University of Liverpool and/or the Philip Leverhulme Equine Hospital?
A. a.’ (Emphasis added.)

Jacobaea vulgaris, common ragwort

Jacobaea vulgaris, common ragwort

Note that I specified the date of 6th September 2011 because this was the day Professor Knottenbelt sent me the email saying ‘I am retired anyway’.
Also in the 6th September blog I wrote ‘Prof. Knottenbelt is often quoted, by the horse owning community, as THE authority on ragwort poisoning so his views deserve careful consideration’. Having given his views careful consideration it is clear that those thinking of calling the professor into their arguments for the harm caused by common ragwort should think twice.

I felt I should give Professor Knottenbelt the opportunity to comment on these discrepancies so I emailed him attaching the email I had received from the University of Liverpool. In answer to my query about his claim to see ‘more than 10’ deaths a year leading him to claim that the number of deaths in the whole country ‘for sure it is not less than 1,000 horses per year’ when his unit has seen only 18 cases in five years the professor replied;

‘I am at a loss as to how these figures have been obtained anyway.  The possible reason for that is that these cases are simply those that have gone through admissions reasons in the hospital.
‘My figure that I have never varied from of 500 a year in the UK is based on my minimal number and represents 1 per year which historically has been the minimum number we have ever encountered.   Our case histories are held as final diagnosis not an admission suggestion!’

Jacobaea vulgaris, common ragwort

Jacobaea vulgaris, common ragwort

Note ‘not less than 1,000’ has become 500 a figure that the professor says he has ‘never varied from’. And ‘more than 10’ deaths a year has become ‘1 per year’.

On the matter of his status, the professor said that he works part-time and receives a pension so he considers himself 'retired'.

I said on 6th September that I was not interested in making an ad hominem attack on Knottenbelt and I have not followed up today’s email from him because I doubt if any light would be shed on the issue by doing so.

But I thought I should blog about this at rather greater length than my usual contributions to give people the chance to decide for themselves what value to place on Professor Knottenbelt’s claims and the credibility of those who rely on them to support their anti-ragwort campaigning. 

I will repeat what I have posted many times before on this subject. There is no doubt that Jacobaea vulgaris, common ragwort, is poisonous and has the potential to do great harm but misrepresenting how extensive that harm is serves no purpose.


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