Mary took the box inside and set it beside her couch, sifting through it. The first vial that caught her eye was clearly labeled "Cow", and she wasted little time in drinking every last drop of it.
Her body began to feel warm all over, and she soon discovered that her skin was becoming pale and slowly coating itself in a thin layer of white fur. Black splotches coated her body soon afterward, and her view of her body was quickly interrupted by her swelling breasts. They grew outward and filled up her shirt, swelling nearly as large as watermelons, her nipples pressing to the fabric prominently.
Something on her stomach, or rather, below it, seemed to be pushing out from her body, against the button of her shorts. Before she could unbutton them herself, the button popped off, and whatever was growing beneath it also took the liberty of forcing her shorts to unzip as well.
Glancing over her chest, Mary soon found a growing udder had flopped out into the open and was tugging her shorts down. She decided to oblige it and remove her shorts, and the thong beneath them, as her transformation continued.
Her feet had soon formed into black hooves, and a light tail sprung from above her rear. Her rear itself had put on a bit of weight as well, wider and far juicier than she remembered it. Her hips widened, and wet spots had begun to form on her shirt.