It is do-able... but your life will change dramatically.
Juggling the horses and kids is difficult. I managed to enjoy a whole 3 hours child free while the oldest started playschool and spent quality time with my horses.. and that lastest for a whole 5 months before I found out #2 was on the way.
I still get out to my horse. I don't ride half as often as I'd like, there are plenty of times when the car is parked outside the stall while I muck out and feed with the kids sitting in it. Like was said before - buggies parked by arenas, attempts to smother barn cats with love... been there, done that
Lets face it, my body is warped and I'll never see a bikini again, my hours with my horse have decreased but unheard of amounts of time, I have little to no piece and quiet, and they completely destroyed my social life - BUT
as a person who people said would never have kids... I have never felt the love and need to protect as I do those two little people. The thoughts of something happening to them scares the life out of me, I could not love anybody or anything as much as I love them. My youngest is now 18 months.. he'll be starting playschool in only another year and a half. In the big grand scheme of things... what is 3 years? I have plenty of time to enjoy my horses for the rest of my life.