Four new positive tests for equine flu have been returned in vaccinated thoroughbreds at the Newmarket yard of flat trainer Simon Crisford. Racing industry is in lockdown until at least Wednesday while the British Horseracing Authority tests horses nationwide. Crisford said In a statement, none of the four horses who tested positive displayed any clinical signs of respiratory illness prior to the mandatory swabbing undertaken last Friday. “All four identified horses have been vaccinated within the last six months along with the rest of the yard and in line with vaccination protocol.” The yard is one of the 174 to be tested because runners from the stable competed at the fixture at Newcastle on 5 February, which had been identified as a potential risk fixture. The virus is generally not thought to be life-threatening, but limits the competitive capability of horses.