Went on a long trail ride today. It was bitterly cold here for the last month so we haven't ridden them for a couple of months until this week. Anyway, hubby's 6 y.o. Mare went into heat. We were riding with a gelding. His owner said it was because we got her hot being ridden and she was around a "new horse". My 4 y.o. Mare didn't go into heat.
Is this normal? I didn't think they went into heat at all in the winter.