It becomes a fad for girls to act like animals. Maybe it's something a celebrity started, maybe it's just one of those sweeping shifts. Either way, it is hip to take on animal characteristics or personality traits.
Small things, considered cute, like eating a lot of tuna and wearing small cat ears on your head, or, like a dog, getting quite excited at the prospect of catch / fetch. However, with time it progresses beyond this.
Women start wearing collars or bells, gradually removing articles of clothing, and soon, a drug releases, with a popular risk-free trial, to get the REAL ears and tail of your choice! Not to mention halt outwardly physical aging (a large selling point even to those who felt themselves "above" the fad). It sells like hotcakes, as anyone might expect.
But soon, things take a turn. The far less glamorous traits begin to rear their head- an unknown side effect of the drug. Cowgirls need to be milked, Doggirls' tongues begin lolling helplessly from their mouths, impairing speech, Catgirls reach a desperate heat, things of this nature.
Ironically, it is at this time that the fad starts to die, but these girls and women have been on the drug too long for the effects to wear off, in fact quite the opposite, they solidify their place in the psyche of the individual. So if you see a boy having to pick up after his doggirl sister in the park, she simply cannot be blamed for that behavior, much less the obvious public nudity, and laws are changed to suit this.
Some retain humanity and continue normal relationships with their significant other (albeit with more primal urges and less clothing), though many are simpleminded, but happy animals, speaking with woofs, or moos. In any case, sex is common in public, originally to accommodate special cases such as the aforementioned heat or "roughhousing" between a couple pets, it was taken advantage of by anyone with a petgirl and is now a standard part of society.
And that's the waaAAaaAaay the news goes.
