Jeff fiddled with the controls again as Emily took another long drink of milk, pressing the button just as she set her empty glass down in the sink. The changes had happened pretty quickly before, and this time was no exception:
Emily turned from counter while absently scratching at the top of her head, where two horns were rapidly pushing upward through her hair. Her ears, too, had grown, flicking and twitching as they enlarged on either side of her changing face, which was becoming more cow-like by the second. Her nose spread wider as it grew, pushing outward along with her mouth and jaw, forcing her eyes further apart as her head expanded and reformed. Her blonde hair was taking on a reddish hue, and as she walked past him at the table, Emily shook her enormous head, causing it to fall over her changed face and obscure her eyes. She didn't seem bothered by her lack of vision though, and continued to amble towards the back door.
Seeing her from behind, Jeff realized the changes had been affecting her body, too. He'd been so distracted by her face that he was shocked to realize her hips had widened significantly, and a ropy tail had pushed out from the base of her spine to dangle behind her, a tuft of matching reddish fur twitching as she walked. As he watched, her clothing dissolved into more shaggy fur, now covering her whole body. She was actually becoming a cow right before his eyes!
Quickly getting up from the table, he followed her as she opened the door and clopped down the steps into the back yard. He glanced down to see that her feet had reformed into pale cloven hooves, and he could see an udder peeking out from between her thighs. As she reached the grass, Emily bent forward, and Jeff watched as her hands changed to match her feet, arms lengthening to correct her new quadrupedal posture.
He'd changed his sister into a full-blown COW, and she was contentedly grazing in their backyard!