The horse was the general favourite to win the Cheltenham race a record fourth straight year, but he burst a blood vessel during training and will not run again this season.
“This is a massive blow to punters, many of whom would have made Best Mate their banker of the meeting. We\’ve taken about 750,000 pounds in single bets, not including things like accumulators,” said Coral spokesman David Stevens.
Ladbrokes estimated that Best Mate\’s absence will cost punters Â£500,000. Betfair had matched bets for 538,000 pounds on him.
Next weekâ€™s Cheltenham Festival, with the addition of a fourth day and a total of 24 races, will “be the busiest four days in punting history.” Cheltenham chief Edward Gillespie is expecting crowds of about 55,000 for each of the first three days, rising to 65,000 for the final day.
Bookmakers are looking to turn over Â£600 million.