For a few moments, nothing happens. Then, Dan feels his skin begin to tingle and prickle. He shifts around in discomfort while the scientist watches, grinning.
The feeling slowly becomes an uncomfortable itching. Reaching to scratch a forearm, Dan gasps as he sees small, brown hairs sprouting from his hands and arms. The hair slowly starts to spread to his chest and back. "W-what are you doing to me?"
The scientist's grin becomes even wider. "Why, you're becoming... a rat!"
"A rat?!" Dan cries out. The fur growing around his upper body grows thicker and longer. Dan holds up a hand, horrified, as they are also covered with brown fur, and his nails grow longer and sharper. Suddenly, he doubles over as his shoulders painfully hunch back. The fur grows over Dan's legs, and his feet slowly stretch, also growing long, sharp claws.
Dan falls to the floor, writhing in pain as his body reforms, his bones reshaping. "N-n-no" he stutters as the fur creeps up his neck; his voice now sounds much more high-pitched. "N-n... nnnngggh!" Dan cries out again. Slowly, his front teeth begin to grow larger, preventing him from speaking, as the fur spreads across his face. His furry skin also feels much tighter, and the scientist and operating table now seem much larger. Is he... shrinking?
Dan grunts as his ears grow larger, and his face becomes completely covered with fur. Suddenly, a stab of pain goes through his jaw. Dan screams, grabbing at his face with his hands - now paws - as it elongates, becoming a long rat's snout. Finally, the transformation ends with a jolt at Dan's backside as it grows a long rat's tail.
The scientist laughs as Dan slowly gets to all fours...