With a sudden jolt, something snaps in your elbows and knees as you feel them twist and realign. You cry out, the sound somewhere between woman and horse as your vision flashes red with pain and your grip on the glass of the observation window starts to slip.
The tingling sensation of your transformation spreads further, traveling down your limbs and into your hands and feet as you force your eyes to focus on your shaking hands and immediately realise the reason for your faltering grip on the glass as you see your fingers starting to fuse.
Your nails are darkening, the transforming keratin starting to spread up your fusing digits as you finally lose your balance and fall to all fours with a thud. Knocked off balance by your fall Liam stumbles forward, the head of his cock pressing against your cervix and driving the breath from your expanding lungs with a strangled gasp as you feel your spine pop and you see stars.
Panting, you look down to see a pair of hooves where your hands had been only moments ago. The shock of it sends your mind reeling, but your body has no time for shock, as waves of pleasure surge through your transforming body with each thrust of the immense phallus ramming into you as Liam resumes fucking you, grunting as his cock pulses and he nears his climax.
Your mind a whirlwind of confusion, fear and uncontained lust you realize that you can no longer stand upright, your new equine legs and realigning spine leaving you trapped permanently on all fours. Despite the situation you can't fight the all consuming lust you feel as you press back into Liam's swollen balls, your leathery folds milking at his cock as you rapidly build towards a second orgasm.
Your whole body is swelling now, your increasingly hairy torso starting to round out as you feel your breasts and neck start to tingle as your transformation spreads to your few remaining human features.