Ok Caleb for New Vegas at least (should be the same for 3):
'One in-game-hour transpires in two real time minutes.'
http://gaming.stackexchange.com/questio … -new-vegas
Buffout's effects last four minutes of game time
So effects should last ~ two hours-ish
So pulled up some stuff on horse estrus cycles. They cycle during late spring, summer and early fall every three weeks or a little bit less than a human woman. And there are 3-8 in the middle of the cycle where the mare is 'in heat' at the peak of the cycle corresponding to human ovulation and a similar spike in hormone levels. Some mares experience something similar to PMS in women often jokingly called 'Pouty Mare Syndrome'.
As for effects of the being in 'heat' the severity of the effects vary form Mare to Mare:
Some mares are grouchy just before estrus, some during and some after. One of my mares behaves almost like a gelding. One is a real "hormone queen" and can get quite anxious and irritable during her heat cycle. The others are more normal in their expression - not a big behavioral change.
Your mare may hardly change when she comes into heat, or she may behave so erratically that you wish you’d bought a gelding. Most fall somewhere between those extremes.
For those with extreme hormonal changes there are drugs like Regumate which regulate the hormonal levels to prevent ovulation and even out behavior. It's a Progestogen and works very much like Progestogen-based birth control pills for human women. Also there are herbal compounds often using things like Vitex agnus-castus (aka Chaste Tree / Monk's Pepper) Berries which are considered to be an anaphrodisiac and are used in human medicine to regulate PMS and historically by monks due to it's anti-libido properties.
So basically hormonal effects on behavior vary wildly and birth control pills can help even out the hormonal changes that happen during the cycle. So basically LewaBolt just needs to be started on birth control pills.
Some source links:
http://www.horsekeeping.com/horse_behav … _signs.htm
http://www.equisearch.com/uncategorized … les-mares/
http://www.equisearch.com/horses_care/m … s-in-heat/