The wish granted, Karissa begins her transformation into a mare. A warm shiver runs over her entire body, like a comforting breeze on a hot day. The shiver ran up her body, fading near her head. Karissa put a hand on her forehead, suddenly dizzy, and awkwardly sat down.
Karissa looked at Mitch, "I guess I just don't go poof?" Mitch shook his head which was now elongated and rather funny looking, somewhere between human and donkey. Karissa nodded and waited for her changes. She didn't have too long to wait. The dizziness had passed and now Karissa put a hand to her belly, rubbing it and feeling bloated.
She didn't notice at first that it was a part of her change, but the bloated and tight feeling grew and soon she became uncomfortable. Karissa rubbed her belly and thighs, feeling how tight her jeans had become. Her change was now noticeable. Karissa moaned in slight pain as her thighs filled her tight jeans to the fullest and kept growing. In fact, it wasn't just her thighs, but all of her legs that were changing. The tight jeans forced Karissa's legs out straight, and she watched helplessly as they grew longer, her feet and ankles sticking our further and further.
The tightness slowly rose up to her belly where Karissa rubbed a quickly swelling belly. The fabric of her t-shirt stretched much more easily than the jeans. Karissa went from having a potbelly to a full barrel chest as her changes flowed upward. A slight tearing sound brought both Karissa's and Mitch's attention back to her legs. Rips were appearing on her thigh sides, show a dun colored fur underneath. Karissa stood awkwardly, her legs painfully tight inside her jeans. She tried to walk a step or two toward Mitch, but fell down on her hands.
"OOpph!" Karissa stopped sooner than she'd expected. Her arms had lengthened to even out with her legs. Now Karissa seemed to swell, once the size of a human on their hands and knees, she ballooned to reach the size of a mare able to handle a large stallion or donkey. Fabric too fragile to hold such a swelling body gave up the fight and tore off, first the shirt, followed shortly by the jeans. Rags fell to the floor, like a grand theater curtain opening, and showed Mitch Karissa as a nearly fully transformed mare. Karissa's body, starting from her crotch had transformed outwardly. A full and quite large rump glistened in new fur and sweat. As Mitch watched with increasingly donkey desires, a sleek tail of silky hair grew out and hid the rump with a modicum of modesty.
Karissa's hind legs had finished their arrangement into full horse legs complete with dainty hooves. The last of Karissa's human body was her arms and head. That didn't last long though. Arms thinned, hands melded into dark hooves and soon, only a human head remained.
Moving her head side to side like she was attempted to crack her neck, Karissa felt the last changes take hold. Her neck lengthened just as a silky black mane nearly popped out. Karissa felt her mouth and nose pull out and away. Of all the transformation, she felt this was the strangest. Her ears also pulled from the side of her head to the top.
Karissa tossed her head and whinnied. She was a mare now! She stood nearly four feet tall to her back. Dun colored with black mane and tail and feeling rather turned on by the whole transformation and being an animal.
Mitch was staring wide-eyed and painfully erect at her. He was still mostly human. He shook his own equine-like head and climbed mostly out of his pleasure induced stupor.