it\'s a hard call though since northern dancer\'s team were way-early adopters of lasix back in the 60s...though i tend to agree with you that it seems pretty unlikely that horses that raced as frequently as secretariat and seattle slew were doing so on lasix. actually, i don\'t know how any horse can run on it--it\'s an incredibly debilitating drug.
i guess it would depend on how many horses ran in all three races on lasix and their relative perfomances, since fresh entries on lasix would create statistical noise. if all horses are runing on lasix in each race, it seems like you might still get a TC now and then even if lasix makes it that much harder for a horse to do it (we\'ve had a lot of lasix runners win two, and still place or show for example--even mind that bird ran in the money in all three).
it\'s hard to judge since you don\'t seem to get as many also-rans trying in all three races like you used to. were sunday silence and easy goer on lasix for the first 2 legs? they both did well in belmont (but that would have been lasix free i think, before NY lifted the ban, but the lasix drain should still have had an effect...)
but the drought could be breeding after all, since only one triple crown winner was sold at auction; all others have been homebreds.