Martin Cherry's Wynn Dot Comma, who upset leading Kentucky Derby (gr. I) contender Eurosilver in the Swale Stakes (gr. III), was euthanized Tuesday after breaking down during a routine gallop at Calder Racecourse.According to the Daily Racing Form, the son of Struggler had nearly completed his regular gallop around 6:30 a.m. when he apparently took a bad step and broke his right front ankle"I don't know exactly what happened, it all transpired so quickly," said trainer Marty Wolfson. "He has always had a problem with his feet but never anything else. And he'd been training better than ever recently. The track was a little deeper than usual at the time the injury occurred. I guess he just took one misstep."Wynn Dot Comma won six of eight career starts, including the Spectacular Bid Stakes (gr. III) and two other stakes. The March 13 Swale victory marked the 5,000th career win for jockey Edgar Prado.Wolfson said Wynn Dot Comma will be buried at his farm in Davie, Fla.