I have 2 mini Shetlands who are 28 and 16 respectively.My routine has generally been keeping them out when nice and in when raining , cold and horrible weather generally . We are due to have minus temperatures this week ( I'm in the south so not seriously minus ) The ponies seem to enjoy this routine but a couple of people have said they should live out to keep their joints mobile and healthy and now I'm in a quandary as I don't want to see them lying down on mud / wet ground.They are both rugged.How do others keep their oldies.