Racing faces a £300m loss if spectators are not allowed to return, says the head of the Racecourse Association.
The sport has already suffered several hundred job losses, David Armstrong told BBC Radio Four’s Today programme.
He was speaking after local health officials told Doncaster Racecourse to stop racegoers from attending the final three days of its St Leger meeting.
Officials say abandoning the Doncaster crowd pilot will cost the track £250,000.
The course was told to go behind closed doors after its opening day when the reported rate of coronavirus infection went above 10 per 100,000 in the Doncaster area.
Premier League chief executive Richard Masters told the BBC on Wednesday that failure to allow football fans inside stadiums will cost clubs £700m during the 2020-21 season.
More than half of racecourses’ income comes from spectators. Reduced revenues will affect prize money, which has a knock-on effect on trainers and owners.
Armstrong, whose organisation represents the UK’s 59 racetracks, hopes new plans for faster Covid-19 tests announced by Prime Minister Boris Johnson could offer sports a lifeline.
“Unfortunately we’ve seen quite significant job losses at racecourses and in other parts of the sport as well, with trainers, breeders and others – but particularly at racecourses the number of redundancies is several hundred already,” Armstrong said.
“We had hoped the pilot events would prove the protocols were working well and we come back to having spectators, albeit with limited capacities, from 1 October.
“I heard Richard Masters talking about it costing the Premier League £700m. It would cost racing up to £300m to go for a whole season without crowds.
“New forms of tests are very important because they are, in my opinion, the key to unlocking the return of spectators on a wide scale.”