I just recently tamed a level 65 cat from near Sylvanaar in the Blades Edge Mountains, which I've named Sprowl. He is a lot more fragile than my boar, but does better damage as well, so I'm going to level him and then alternate between the two depending on what I want.
The odd thing is that although I'm 70, Sprowl is apparently still levelling himself. I've looked at his experience, and it seems to be going up. This is good, because I was worried that a pet only levelled if I was still able to gain experience myself.