All blood samples taken from horses during the Jockey Club's surprise swoop on some of the leading yards in the country on yesterday have proved negative.
The stables of champion trainer Martin Pipe, as well as Paul Nicholls, Venetia Williams, Len Lungo and Alan Jones were all targeted in dawn raids.
But a statement from Jockey Club Veterinary director Peter Webbon today confirmed the tests had proved negative, and that those tests were principally to deal with the well-publicised allegations of the use of erythropoietin (EPO).
He said: "This was principally an exercise to deal with the well publicised allegations of the use of EPO in racehorses.
"Samples from 408 horses were collected yesterday - about 8% of the National Hunt horses currently registered in training - and, following the use of well proven screening techniques, HFL (the Horseracing Forensic Laboratory) have informed us that all the samples tested negative for EPO.
"I hope that these results will serve to reassure the racing public.
"We have spoken to the five trainers concerned and told them that the tests were all negative.
"We have thanked them for their co-operation during the collecting of the samples and apologised if we caused any disruption to their training programmes.
"The Jockey Club will continue its programme of unannounced visits to trainers yards, both large and small, for the purposes of testing horses in training and we shall continue to monitor samples for the presence of EPO."
PA