New vaccination rules brought in as a result of equine flu could disrupt preparations for horse racing's "biggest festival of the year," a Welsh trainer has warned.
Racing resumes on Wednesday after a six day shutdown, but the British Horseracing Authority states all runners must have been vaccinated against the virus in the last six months as opposed to 12 months previously.
Ten horses from the yards of Donald McCain in Cheshire and Simon Crisford in Newmarket have so far tested positive.
Glamorgan-based trainer Tim Vaughan warns a booster vaccination could set a racehorse back two weeks, with Cheltenham just a month away.
"If trainers haven't vaccinated their horses in the last six months, they will need to vaccinate again. They can't run then for a minimum of six days, so it's going to stop them being able to run their horses in the short term," he explained.
"Long term, when a horse has been vaccinated it needs a couple of quiet days. Obviously it'll miss a week of work but it'll also have to miss another week just doing gentle work, building it back up to full swing.
"It's not really what you want to be doing a month in advance of the biggest racing festival of the year."
Mr Vaughan, who has runners at Musselburgh on Wednesday as well as Cheltenham Festival, is relieved he took action when the outbreak started.
"As a yard we gave all our horses booster flu vaccinations last week so it doesn't affect us at all. As soon as the news spread we gave our horses additional boosters so it's working fine for us.
"I'm delighted to get things going again. The BHA have put various restrictions in place which, in my opinion, is for the benefit of the industry as a whole so I have no complaints."