Mary noticed a little empty vial. On the back of it read: Put in the contents of one vial until it reaches up to the line. Then fill the reast with the contents of another vial.
Mary looked through the reast of the vials. She picked out a Red Fox vial and a Cow vial. She poured one half of the Fox vial, and one half of the Cow vial.
"Well, here goes!" Mary swallowed the entire content of the new FoxCow vial. Immediately, she felt a strange feeling in her stomach. "I must be digesting it right now." She went into her bathroom, stripped down, and looked in the mirror.
She felt a strange sensation obn her face, as though one were stretching it out. She opened her mouth to let out her tongue, which was now around 8 inches long. Her nose began to blacken, and her mouth moved upwards, merging with it. Her face started pushiing out, and soon she had a fox snout.
She looked at her hands which had become covered in soft, black, fur. A cow like pattern formed on her arms and legs, and her skin began burning.
"Oh, god, why did I do this?" Her skin began bubbling painfully. It thickened into a leathery hide.
Her shoes began stretching out, and burst apart. Her toes hardened, and merged into hooves.
Her ears turned pink, and grew to a great size, becoming cow ears.
Her spine cracked, and a hite fox tail with black splotches grew from her backside.
Horns began growing from her skull, big white horns that protruded from the side of her head.
Her breasts began bobbing up and down. Mary felt pleasure course through her body as they increased in size, only for her to grow 2 more identical breasts right under them.
Her stomach grew in size, as did her butt, giving her nice curves. From under her stomach, a pink thing began swelling in size. It was Mary's own udder.
Finally, the transformation was over. Mary looked at herself in the mirror. "I... I feel absolutely perfect!" She began laughing, and started feeling her arms. "Oh, this fur... it's so soft and warm, and it's mine!" She bounced her breasts. "And I have this wonderful new figure! I even have a nice belly!" She jiggled it a little and giggled. "And these wonderful ears, and the horns and the tail, oh god, this beautiful, big, soft," She hugged her tail, which was almost as big as she was. "...fox tail! And I'm going to be like this forever!"