I like your choice of background, it makes for good contrast, and you've got good detail on the whiskers.
The light could be brighter, but on the other hand the shadows give this a mysterious atmosphere, taking it beyond the usual pet shot. I'm not a big fan of cats, but I like this portrait of one.
The tips of the ears are clipped off - it's not too distracting in this case, but I've also noticed this in your son's portrait (his right hand), so perhaps it's something you should be careful about (unless, of course, it is obvious from the photo that that was the intention).