Put your bitch on Norethisterone 5mg daily, if you keep a record of her last season ie what date she broke, start giving her the pill a month before she's due to break again, then take her off it after the hunting season.
I find it has no side effects with my bitches.
even racing jeff ? my mate races greyhounds but sees a drop in performance....don't suppose losing a yard or so matters to a lurcher but racers....