Take the family cat. It needs vast improvement. It now longer needs to hunt, so the claws can go. I'm willing to bet that a scratchless cat is worth a few million to its inventor. Then you turn your attention to flea resistance. Fleas bite and eat the cat's blood. The future cat would have genetically modified bloody that is stinky to fleas and they would find it repulsive. The cat would no longer have fleas. Just have lots of Febreeze around if the cat cuts itself, but it is a small price to pay to get rid of pestilence.
The next step is to prevent shedding. Cat hairs will be genetically modified to wither and crumble into dust from the top down. Instead of cat hair clinging to everything, a quick pass with the Swiffer gets the floor clean.
And finally, we will cure the "aloofness" gene in cats and transplant the dog "friendly" gene. The cat will be waiting at the door, ready to greet you as you come home from work. It will jump up on you, but it won't scratch or shed. It will be the perfect pet. It will supplant the dog as man's best friend. That would be a dog-gone shame.