Horseracing in the UK is on hold until at least Wednesday while the British Horseracing Authority (BHA) tests horses nationwide.
However, four new positive tests have been found in the Newmarket yard of flat trainer Simon Crisford.
In a statement, Crisford said: "All horses at Kremlin House Stables, totalling 92 boxes, undergo a strict vaccination check and programme on their arrival.
"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 BHA’s initial suspension came after the discovery of three horses testing positive for the disease, all from trainer Donald McCain.
At the time, a spokesperson from the BHA said: "This precautionary approach is intended to ensure we put the health of the horse population and control of the virus first, and avoid any unnecessary risk that might come from returning to racing too quickly."
