Obviously, as you well know but refuse on emotional religious grounds, all life evolves, has evolved and will continue to do so. But asking how a dog "becomes" a cat shows a serious naivete to the entire subject - and it's not something that I'm willing to go through with you.
I would advise that you engage in study - somewhere other than creationism.com. As a start - because it's written for the layman, I would suggest Dawkins 'Greatest Show on Earth'. If you're at all interested in the truth of the matter, you'll take that advice.