Same in Creative too(they should really add a both button).
you know how trees are very close to each other? like 1 block away from each in most dense forests? its a pain to have to hack your way(physically) through another set of leaves when there is a clear opening 1 block wide X blocks high!
Picture 1: cant go through because the horse takes up 2X2 blocks(4 total in a cube). recommend 1 width 2 high.
picture 2: cut one leaf still cant get through
picture 3:cut a second STILL CANT GET THROUGH
picture 4: cuts a third and finally gets through
it would be useless to show you in survival because the Entityhorse.class is unchanged. it would be exactly the same problem.
a simple solution would be as is:
// where canMove() is a boolean field or something.

public void inBetween() {

if (Entityhorse.getY() <= Block.getY()) {
//the can move through is just an idea of what the horse can do if it meets at this //point

canMove() = true;

return canMove != null;
}
if (Entityhorse.getX() <= Block.getX()) {
canMove() = true;
return canMove() != null;
}
/* probably don't need this one */ if (Entityhorse.getZ() <= Block.getZ()) {
canMove() = true;
//end
}

or something like that.
(csd is not generated cannot properly show you the syntax like this very well)