"Holy shit, Jeff... you're almost there! Only your head is left to change!" Dean was giddy with excitement - they were sure to win the upcoming race if his friend was as powerful as he looked!
Meanwhile Jeff was feeling strange, everything was loud and bright and hard and echoing... he stamped a hoof and shook his head, the fear that something had gone wrong growing in his brain even as it shrunk. The cerebellum shifted upwards as the spinal column reoriented itself to exit the back of Jeff's skull, and with a few audible cracks, Jeff found himself naturally looking forwards instead of staring at the floor. His eyes closed though as a stretching sensation reached his ears - they expanded, growing pointed even as they slid slightly backwards and up, flicking in all directions with a new sensitivity.
The last of the heat that had suffused his body finally seemed to center in his face, but his eyes remained closed as his nose began to push outward, widening as his jaw elongated. His canines flattened, teeth rearranging for his new diet while his cheeks plumped and his forehead broadened, spreading his eyes to either side as they enlarged, long eyelashes fringing each one. He blinked, disoriented by his new dual-perspective, and tossed his head, letting out a loud "nnehhEEEIIIIIIiiiiiigh!" followed by a few fearful snorts.
On one side of him stood a boy, seemingly frozen in place, but the rest of this loud, echo-y building seemed to be empty. Comforting smells of hay and wood and leather flooded his nose, helping to calm him a bit.
"Shhh, boy, shhhh. It's okay, you're okay." Dean approached the enormous black stallion that Jeff had become, murmuring soothing words and moving slowly. The horse wasn't secured and wore no bridle or halter, so Dean wanted to make sure he didn't spook and run out the open door of the stable. Maybe altering the settings so that Jeff wouldn't retain any of his human thoughts or memories hadn't been the smartest idea...