It is the worst outbreak of equine flu for 10 years

More trainers are noticing symptoms of the disease which can put horses out of action for 10 days and tires them.

It is bad news for the headquarters of racing in the UK with only weeks to go before the prestigious Craven Meeting in two weeks.

So far 10 yards have been affected by the outbreak of what is thought to be a new strain of the virus.

Hundreds of horses are now being tested for the virus which is not fatal but does tire the horses.

Worst outbreak

Equine flu is the most virulent disease that can hit racing stables.

Vets and scientists at the Animal Health Trust in nearby Kentford say this is the worst flu outbreak in Newmarket for more than a decade.

Horses which have been vaccinated against the virus are succumbing.

Dr Richard Newtwon, of the trust, said they feared the strain in this outbreak had changed significantly from the ones contained in the vaccine.