You grasp your member between your fur covered fingers, rolling it gently to feel the plushness of your newly grown fur against your shaft. A tingle travels up your tail and spine as you let out a small gasp- through the arousal brought about by your transformation, your dick seems to only have gotten more sensitive, the touch of your hand enough to stiffen it. Your toes and hoof curl at the sexual sensations wracking your body, only amplified by the intensity of your change. You take your other hand and cusp one of your forming breasts, letting yourself sink into the ecstasy of the moment.
Your personal exploration is interrupted by a sudden but familiar clenching in your nethers, the same kind that takes hold as you orgasm. The suddenness of it surprises you, as you haven't even gotten close to your plateau. Nevertheless, your shaft starts to dribble out seed, the warm fluid slathering over your hand. It is somewhat embarrassing and not as satisfying as you'd like, especially as the clenching in your loins ceases to let up, and the flow of cum goes for much longer than you've learned to expect.
You let out an uncomfortable groan, your knees buckling as the pulling in your nethers continues. This was unreal- there was no way this could keep going! And yet the pressure mounts in your balls and pushes through your cock as more cum, the puddle of spunk between your toes and hoof growing until finally, the flow stems, leaving your tip dribbling with the last of your seed. Only now do you realize just how much you've been sweating... and cumming, too.
But it still isn't over. The grasp on your balls only intensifies, throwing you onto your knees. You hiss through gritting teeth, using a hand to rub your sack to alleviate the ache. You're terrified to feel first hand your nuts slowly withdrawing into you, pulling away from your scrotum and squeezing their way into your abdomen. You've felt this sickening, creeping feeling before, when you were an idiot kid who smacked their jewels into a rail- the awful ache that spreads its way up from down low before seizing your entire body. You throw a hand out to catch yourself, dry heaving and drooling onto the ground as your nuts dragged their way through internal cavities you didn't even know you had, before finally settling into place, somewhere behind your intestines.
You cough a few times, distinctly noticing the lack of a jostle in your sack. In fact, with nothing to hold, the skin of your scrotum draws taut, leaving the space under your dick flat and smooth. The lack of weight behind your member was impossible to ignore.
However, you didn't have much time to lament the loss of your pair. Your dick, still stiff and erect, even after all that's happened, begins to diminish and withdraw, pulling into you. Your foreskin recedes from the reddening tip of your cock. You want to reach down and touch it, but it burns so fiercely of pain and arousal, you are afraid what might happen if you did. Not that you had to worry about ever accidently touching it again- the flesh where you scrotum once was itches terribly, a vertical crease digging out a cavity between your legs.
You shout- the cleft digging its way inside of you like an invader, as if someone had taken a wet sponge on the end of a rod and slowly pushed it inwards. Your fingers, toes, and hoof dig at the ground, trying to distract from the forming vagina. Trying to ignore the blossoming of cervix's tight entrance. What you can't ignore, however, is the womb- how it slowly balloons to life inside of you, pushing organs aside to make room for itself... and any foals you might wish to bear.
You clutch your belly, face red at the thought of bearing foals... and how lovely that sounded to your pointy ears.
There was one last tug in your nethers as your former penis completely withdraws and nestles at the edge of your thick, leathery labia as a clit. The muscles in your new sex relax and you can finally let out a sigh of relief. A warm fluid drips out of your marehood and down your leg- you can smell it, the musky odor of a mare in heat. A pleasing warmth radiates from your ovaries as they flush your system with estrogen, smoothing out the harder edges of your body and heightening your emotions. You let out a squeal of joy- you were going to be a beautiful mare, and you know you will make an excellent mother.