Jeff was still attached to Sam by his knot when she felt her legs, followed seconds latter by her arms, tingle. There was a slight sensation as she felt the bones shit in her hips and shoulders and watched in fascination as her ankle slid upward from her foot, slowly shifting into a dogs foot. Her arms did something similar, as her fingers shortened and the claws formed on her nails. It took little time for her fingers to shorted so much that she was sure they were all but useless.
It wasn't long after that she felt a strange tingle over her entire body, nothing dramatic but something felt final about it. When it was over, she felt done, though she wasn't sure what else had changed. Once Sams knot has shrunk enough, she was finally able to stand on her new four feet and took an experimental step forward. It took a few seconds, but after a few steps it was natural.
She padded over to a mirror on the way, then lamented that she was too short on all fours, so she went to a nearby bathroom and balanced her front paws on the counter to get a good look at herself.
Her face was still human, though she now had a couple of prominent canine teeth making her almost look like a vampire. Her ears were now tall, much like the German Shepard she'd decided to join. Her nose was a bit darker, but still human. She smiled, and without thinking her suddenly much longer tongue lolled out of her mouth while she panted. She had six breasts now, each far larger than a dog would have but normal on an adult woman. She also had a very thin coat of fur on her body, much shorter than Sam, but enough to show off the markings of a pure-breed German Shepard. She left the bathroom wagging her tail.
She jogged over the the dog door in the back of the house, eager to feel the sun on her new body.