I enjoyed trying this exercise and I feel that the end result, although short, is really powerful and I want to use this technique in my writing:
Rascal’s breathing quickened into short, sharp pants. He licked his lips and felt the fur on his neck stand bolt upright.
He knew the boy was there, walking towards him; he could smell him. He couldn’t seem him, though. Not yet.
Rascal’s body all at once became rigid, his four legs locking out.
He couldn’t move.
His vision started to sway as the sound of his heartbeat pounded in his ears, deafening him.