Depending on the state in which the BC is held, they may not be able to ban Lasix. You can't just take your horse off when you want and then go back on when you want. The BC to my knowledge has no power to supersede the rules of racing in an individual state so I don't think this is a settled issue.
By the way here is an interesting article from years ago when everything ws supposedly wonderful
http://articles.latimes.com/1990-10-...1_horse-racing
Another one
http://articles.baltimoresun.com/199...orsemen-l-word
http://articles.latimes.com/1992-05-...le-crown-races