bleach will kill thursh, but it will also kill the good cells on the frog....same for any "thrush" medicine. My farrier swears by applying a topical treatment for Mastitis in cows on the hoof once a week and that will help with thursh.
I use it for Sonny and though I've only used it once I did notice a good improvement. The normal thrush smell that I'd smell when cleaning out Sonny's feet was gone in all but one foot (the one that had it the worst) but it did look alot better.
Tractor Supply sells it in their livestock section...it's called Dry-(can't remeber the last word for it). It comes in a white box with 12 suringes in it and costs about $14. So far I am pleased with it
Also my farrier recommended every day apply a Apple Cider Vinager/water mix (50-50 dilution) on the hooves. It will change the PH of the hoof making thrush not able to grow more (but it WON"T kill the thrush that is already there).
With the fields are extremely muddy more than likely she'll have thrush until the pastures dry out. Depending on where you live, more than likely Jubilee could have thrush all summer long.
Thursh lives in the moist areas...cleaning her hooves everyday, letting her be able to stand on a dry spot (not meaning a stall...just any random dry spot), and applying the Apple Cider Vinager solution will help keep thrush away, but if the pasture is always muddy, the thrush may come back.
Also, make sure it's just mud and NOT horse poop...that will cause thrush to grow.
Good luck with Jubilee...me and Sonny are going through the same thing! Keep us updated