No sooner than Tom spied the curled rat on the vial than a sharp pain went through his abdominal, causing him to drop the now empty vial.
"Are you OK?" Matt asked, as he moved to lend a hand.
Tom felt like his body was on fire, skin itching and cramping. He was trying to tense up, to keep the feeling down but it was coming on stronger and stronger. He could feel the lump growing in the seat of his pants, bulging out while he could feel the hair on his arms and legs not just standing, but growing.
Tom reached out for Matt, his arm feeling shorter already in his baggier shirt, and both could see his fingers had elongated, much like his sharper nails.
"Help me!" Tom gasped, before his voice cracked into a squeaking cry, his face starting to crack and push out.
Matt backed away, not able to stop what was quickly becoming of his friend. Fur was sprouting all over him as time shook and shrunk, more squeaks and words like 'help' and 'scared' could be hurt until his shirt grew too large.
In side, Tom watched his face reshape in front of his eyes, whiskers and twitching black nose a growing reminder of what he was rapidly becoming. Tom's hips jerked as his body quickly worked to expel any human seed. Falling to what were closer to paws now than hands, his balls, now spent pulled in while his cock shriveled away.
Intrusive thoughts of being mounted and a growing heat under his tail led Tom to the conclusion that not only was he losing his humanity, but his gender to. His mind was fighting to keep the instincts out while his body cracked down the last few inches until Tom's college education was replaced by little more than a rat's needs.
Matt knelt down and poked at the lump in Tom's clothes. He reached in and grabbed something and pulled out a squeaking female rat. "Tom?" he asked, smiling at the sight.