Feeling his heart beating excitedly, Dustin brought the vial to his lips, pouring its silver contents into his mouth. The serum tasted strange, yet oddly sweet... it was a flavor that he could hardly describe. Even as he finished draining the vial, he could feel a warmth forming in his body, spreading from the top of his head to the tips of his toes-
"U-urk!" The vial slipped from Dustin's grasp, shattering on the floor as he clutched his stomach. Weird sensations spread through his body... his stomach churned, hands and feet tingled and cramped, and he started to perspire heavily. "This is really happening..." he muttered to himself as he dropped to his knees.
Dustin's skin itched, as strands of grey fur sprouted from every pore. He shuddered and grunted, trying to scratch at his body as his ears turned pointed and lupine, shifting towards the top of his head. Dustin's hands suddenly twitched as his fingers grew shorter and stubbier, fingernails sharpening and pads forming. He dropped to his hands and knees, clenching his sharpening teeth in discomfort.
His feet stretched, heels rising off the ground as they snapped and shifted into digitigrade paws. Dustin whimpered, dropping to the ground and convulsing as his innards shifted, bone structure reforming. His nose and mouth stretched forwards into a muzzle, nose turning black and wet as his eyes turned yellow.
A few minutes later, Dustin was a fully-grown, if not slightly larger than average, wolf! He got up onto his four legs, instinctually letting out a loud HOOOOOWWWLLL...