You eagerly dig through the box, tossing aside all sorts of masks and other costume pieces, that either you couldn't wear as your head was no longer human, or that you just simply had no interest in, reserving hope for something better. Soon you find it, a big mess of brown coarse fur, folded up neatly at the bottom of the box. You unfold it curiously, only to find that it's an entire, full sized, horse body, complete with hooves, tail, and of course, a giant horse cock, complemented by a set of baseball sized testicles. This is it, this is something you gotta try!
It's a bit unwieldy, but you manage to get your legs into this behemoth of a costume, painfully squeezing your feet into the large hooves. That pain only intensifies as the costume begins attaching itself to your body, slowly inflating as you bones and bodily organs morph into that of a horse. You grind your teeth together, determined not to let out a loud yelp that would bother your neighbors and prompt them to investigate it's origin. It's not long before the pain ends however, you sit still and pant for a moment, unsure of how you feel about what just happened. You glance down however and marvel at your horse legs, stroking the brown fur with your hand. You trot over to the nearby mirror and admire yourself. The Husky head still remained, but everything else was basically that of a centaur.
You let out a loud bark of glee, satisfied with your new form, waking up Cassey. She looks up at you and tilts her head, confused once more, but that doesn't stop her from walking beneath your new, massive frame. You can't see her, but you're definitely not going to move around with her under there though. Suddenly, you feel her warm, wet tounge slide down your sheath, and again, and again. You can't let her do that...can you? It goes against any sane human thought you have left. But as she continues to slide her tounge down your new horse cock, your new dog thoughts take over. With each sensual lick, you feel your cock fill with cum, growing more and more full with each one, soon dripping with your thick centaur cum. She keeps stimulating your long organ until you can take no more, as you let loose a spray of seman, creating a pleasure you have never felt in that capacity. You moan loudly, fully pleased by the large rupture of thick yellow cum from your shaft.
Without any noise, your dog, trots out from under you, lying back down onto the couch, going back to sleep, as you continue to stare into the mirror, motionless, and deep in thought.