Experts can’t be certain how many horses die from ragwort poisoning, although conservative estimates start at 500-1,000 per year. Some victims graze in fields of the stuff; some eat ragwort-infested hay. Some are accurately diagnosed via blood tests, liver biopsy or post-mortem, while others die undiagnosed.

Professor Derek Knottenbelt has been working with a team at the University of Liverpool for the past few years to develop a test that will be able to detect whether a horse has eaten ragwort. The test is being designed to act as a useful early warning and is on track for completion next year.

“In the 1970s-80s, a researcher devised a crude, complicated test to detect ragwort in laboratory animals. A few years ago, we decided to develop our own test,” explains Prof Knottenbelt.

“The alternative is to go through hay, picking out strands of ragwort. ADAS [the former governmental advisory service for agriculture] had a hay-testing machine in the 1990s. But you never got the bale back, and even if it was OK, your next bale might have ragwort in it because it usually grows in patches.

“Liverpool has the world’s leading scientific group working on proteomics, through which individual molecules of individual proteins can be identified. One molecule of ragwort could show up in blood. Two PhD students are working on it, under Professor Rob Beynon. They’re trying to determine how sensitive the test can be, depending on how much was eaten and when.

“We hope yards will use the test routinely. A 10-horse yard could take blood from two horses every month. If the horses were fed from the same sources, a positive would indicate that all 10 are eating ragwort and the owner could investigate.

“We’ve had funding from the Home of Rest for Horses, the Bransby Home of Horses, the International League for the Protection of Horses, Dodson & Horrell, Sue Pike Equine and Animal Rescue and countless individuals and organisations, but we need more. We hope the test will be usable next year, although the cream on the cake would be saliva, hair or urine testing, which is still some way off.”

Rowan Moore, a PhD student working on the research, says: “Ragwort poisoning cases are commonly defined as either acute or toxic, and little is known about the relative signs or the damage induced by each form.

“In developing this test, we can’t administer such a toxic plant to horses, therefore much work is based on modelling this process in vitro [in test tubes rather than an animal]. Secondly, most previous work has been based on species other than the horse. Although cross-species comparisons have sometimes been consistent, we can’t confidently extrapolate findings from other species to the horse. So we require samples from ‘suspected ragwort poisoning’ cases.”

Prof Knottenbelt would like to hear from anyone who knows or suspects their horse has eaten ragwort and anyone whose horse has been diagnosed with ragwort poisoning. E-mail knotty@liv.ac.uk

  • This information was extracted from a veterinary feature published in Horse & Hound (29 September, ’05)

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