Trainers and racecourses have been told to be on guard after it was revealed Victor Dartnall's Devon stables have been temporarily shut down following an outbreak of equine herpes virus in the form of equine neurological disease.
Dartnall, whose stables are at Higher Shutscombe near Barnstaple, had runners as recently as Saturday at Wincanton, while his last winners came at Exeter and Chepstow earlier this month.
It is possible his horses may have been carrying the disease before they showed any symptoms and while it is difficult to spread, the British Horseracing Authority is taking every precaution to keep the outbreak under control.
In a statement, Professor Tim Morris, BHA's director of equine science and welfare, said: "We have been working with the trainer and his veterinary surgeon to ensure that the correct, robust security measures have been put in place.
"It is in theory possible that horses may have been infectious before the signs of the disease appeared. We have therefore alerted racecourse, trainer and veterinary representatives to possible exposure, but stress the actual risk of transmission of this virus in a controlled raceday environment is relatively small.
"This emphasises the importance of trainers being vigilant for signs of disease and in particular they should refer to the NTF Code of Practice for Infectious Diseases of Racehorses in Training, which contains specific advice on surveillance and what to do if they have concerns that a horse in their care is showing signs of the disease."
A statement on behalf of Dartnall said: "Over the last few days we have suffered an outbreak of a neurological disease in some horses. Initial test results support the cause to be neurological herpes virus. We are working very closely with our vets and the BHA and we are hopeful that we have the situation under control."
BHA spokesman Robin Mounsey said: "Obviously no entries can be accepted from the stable until the outbreak is cleared.
"The racecourses where Victor's horses have raced in the last couple of weeks have been informed. They will carry out their own procedures for ensuring the racecourse is completely clear of infection.
"They are precautionary as it is a very difficult disease to spread. Everything is being done as a matter of thoroughness. It is dreadful news for Victor's yard. For racing it is an issue that is very easily contained. Victor has done everything spot on. He's quite distraught and it is very sad news for him."
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