Pretty quickly if it is to stop her having seasons. If she's out of season when you start the Regumate, she shouldn't come back in until the Regumate is stopped again.
I thought the point of using Regumate was to regulate the hormones? Hence how it works to improve behaviour in mares. Can it be used in other horses too?
I found Regumate to be very good value for money, the doseage my mare required cost me approx £1.50 a week, and started to show effacts within a few days. Wild killer best to soppy loving mare in no time at all!!