Dan whined. He wanted to try to reason with Kat, to apologize and try to talk her out of this, but with his canine voice he just had to stand there and watch the brown fur sprout out from around his claws. As the fur spread up his arms, it got darker until it was jet black toward his elbow and beyond. It was like a wave traveling all over his body. His normal body hair, even his head hair, was gone. He looked in the mirror on the wall and saw himself. It would have been kind of comical, if it weren't real: he was a young man covered in short black fur everywhere his clothes didn't cover, except with brown polka-dot-like eyebrows, brown forearms, and and a big brown region around his mouth and nose. As far as he could tell, the fur was probably all over the parts that were covered, too. He couldn't resist, he had to check something...
Dan pulled his pants open in the front so he could look down into them. Oh, man! Sure enough, his dick was covered up in the stuff, too. It actually looked like some kind of weird black pouch hanging tight against his groin.
"Typical boy, always thinking about that first," mocked Kat. Dan closed his pants again in embarrassment.
Dan's face started stretching out and his brown-furred mouth and nose became one big mass of bone sticking out in front of him. Little black dots started to appear as whiskers grew in. The boy reached up and grabbed the new muzzle in both hands, before his ears distracted them with their own swelling. They felt almost paper-thin in his hands as they turned into the black-furred flaps he'd seen on some of those attack dogs in the movies. "This is really happening, she's turning me into a dog!" he told himself in shock. His lack of ability to sweat took it's toll, and the heat made him open up his black lips and let his long pink tongue come tangling out, showing off his now appropriately named canines. Dan tapped a tooth... sharp!
He then had to watch and feel a strange sight: his hands lengthened and his thumbs shrank, until the thumbs were little dew claws. The fingers were growing thick back pads out of the bottom which made them feel puffy. His elbow closed in tightly against his chest and he couldn't move his arms as much anymore. Similar feelings attacked his legs, pushing him up on tiptoes and causing him to wobble and topple over onto all fours. His hips thinned out into the sleek haunches of a dog and caused his pants to fall off and settle around his brown-furred hind-paws. He looked back at his changed body, still panting. Feeling the tips of drool dripping off his long tongue was humiliating, but he couldn't stop. He turned his head back up to look at Kat, seeing the wicked smirk on her face.
"Looks like my new best friend is almost finished!" see said with a chuckle.
"What else could there be?" he thought, thinking of all the ways his sister had already reduced him to the state of an animal. Of course, Dan new what had to happen next, but he still wasn't ready for the sudden loosening feeling above his butt. First came an unnerving awareness that he could wiggle his tailbone, and then came the swelling feelings as it became much more than just a bone. He grimaced and then looked back at the new limb. Kat watched her brother try out his new appendage, first waving it out of curiosity and then pacing around in circles trying to see it better.
"Aww, look, puppy's chasing his tail," she mocked in an adoring tone of voice.
Dan abruptly sat on his haunches, trying to look as dignified as possible. But he knew he couldn't with his tongue dripping slime out of his mouth, his fuzzy tail flopping around, and his big black dick pouch hanging out in full view. He was furious at his sister for turning him into a dog. He let out a low growl.
She swatted him with a newspaper. "Bad dog! You are going to learn to respect me for once. You know you will, because if you don't I can make this all much worse. Now lie down..."
Dan angled his front paws further out in front of him until his half-brown forelegs and his chest were flat on the ground.
"Good boy! You used to tease my best friend's Rottweiler, and now your mine. Let's go to the park!"