It was as Matt was starting to look bigger and he could feel his ears moving up his head that Tom knew that this wasn't going to stop until the inevitable conclusion. Or so he thought.
"My shirt," Tom asked, his voice raspy and a bit higher pitched.
Matt was slow to comply but seeing as his friend was about to be an animal, he obliged. It came off easily as Tom's torso had thinned and shrunk so much. It was also then, aided by his boxers dropped around his forming paws, that Matt realized species wasn't the only big change Tom was going through.
"Oh man, that's hilarious," Matt giggled, pointing at Tom's chest.
Looking down, he was shocked to see nipples growing down his belly even as white hairs sprouted to cover around them. Reaching lower still, Tom's eyes went wide at the feeling. He gasped, rather she, gasped at the new female sex she poked at with long, deformed fingers with black nails. It was bending over, and the shock, that caused Tom to fall to all fours.
Matt could only watch his friend's body pop, crack, reform and sprout more fur. Tom was beginning to realize the changes weren't physical alone as his memories and mind started to struggle to hold on to humanity as well. Soon all that college education was eroded away by scavenging, raising a family, and mating. He regretted ever drinking the vial but the last thought was that he would likely get knocked up. Just then, Tom was fully skunk.