No, 18x18x36 isn't big enough for an adult panther.
But for the rest it looks ok as far as I can judge.
I would add some slightly thicker branches to help wear down the nails a little.
On your setup I also don't see much reason to be switching to 10.0 ... A reason to switch would be having foliage between lamp and animal. Otherwise it could likely do more harm than good.