Perhaps it was because he was already an animal that the change happened more quickly? Or maybe it had something to do with the fact that he was smaller, and the transmittance had a shorter distance to travel. Whichever the reason, Jake felt that something seriously wrong was happening.
He felt his bones stretching. He could almost hear them lengthening along with his musculature. His fur became thicker and more coarse. Almost prickly in comparison to how a modern day feline relative would feel. His maxillary canines grew in size and length, until they were almost tusk-like in his mouth. When his neck reached a certain width, his collar popped off and fell to the ground.
When the transformation was complete, Jake was far from the innocuous household feline. Anything but. He was nothing short of prehistoric. And feeling the bloodthirsty instincts of such.
He opened his jaws in a loud growl. A growl that almost frightened himself.