Mary reached a hand up to her face, noticing that her nose looked a little different, her eyes seemed to be getting further apart. Her pupils looked strange too, a bit oblong, and her eyes were more golden than their normal brown. As she watched, her mouth pushed out into a strange muzzle, her nose widening and reshaping as her cheeks sunk in a bit along her elongated jaw.
"What was it you gave mehh?" she bleated out, turning back to where Kelly sat on the couch. Her friend had stopped smiling, her eyes wide as she leaned forward and took in the changes happening to Mary.
Stretching out her hands, the young girl clenched them as cramps wracked her body. When she tried to straighten them out again, she realized that they too had changed: her palms had thinned and elongated while her middle fingers thickened. Her thumbs were rapidly disappearing while her pointer and pinky fingers shrank a bit and were pushed back behind the others. Her nails were thickening and encasing the tips of her digits, darkening a bit as they did so. Looking down, Mary could see that almost identical changes were occurring to her feet, her heels having stretched way back and lifting so that she was unconsciously balancing on her toes... or... hooves?
"Holy shit!" Kelly exclaimed. "This stuff actually works! I mean, seeing you as your younger self was one thing, but this is Magic! You're turning into an animal!!"
Mary squinted back up at the woman, turning her head as she realized she could only view her from one eye at a time now that her nose had protruded to block her forward vision. "Meeehhgik. Ehhhss!" she closed her mouth, stretching her neck as she felt it elongate and tingle. Her vocal cords had changed as well, and her tongue and newly shaped jaw were making human speech nearly impossible. "Baaaahhhck!" she bleated forcefully, stomping one hoof as she glared at Kelly.
Suddenly the room seemed to grow around her - she felt like she was falling in sharp spurts, as if an earthquake was affecting only her. Losing her balance, she fell forward onto her fore-hooves, spreading them wide on the carpet. She was now awkwardly splayed on all fours, her hips higher than her shoulders but quickly lowering as her legs shortened. Her limbs thinned even further than those of her 12-year-old body, while her torso rounded out slightly.
A pressure built at the base of her spine, and Mary found she was able to turn her longer neck far enough to view a tiny tail forming, quickly growing out to about 6-inches long! Her clothes hung around her body and she noticed she was only as tall as the coffee table. She must have lost over 70 pounds in the last few minutes! Squirming a bit, she lowered her head until her t-shirt could slide off, then daintily stepped her fore-hooves free of the fabric. A light fuzz had sprouted over her body, and Mary was finally sure of what she was becoming. A cynical part of her brain whispered through her fear: Well Mary, now you have a little lamb!
Kelly sat in awe gazing at the baby animal her friend had just become. She didn't know whether to believe her own eyes, but when she slid to the floor and reached out a hand, the lamb tottered over to her and attempted to climb into her lap. Kelly tentatively stroked the fluffing white wool that had grown to cover Mary's body, thinking about her next move.