I agree, stitches should be out before you bathe. I accidentally bathed a dog that I didn't realize had just been neutered (he was a foster), and he was fine, but it is better to be safe. If your dog has short hair, you could use pet or baby wipes all over. If his hair is longer, they are still useful to touch up feet, face, and potty areas. I know they can get stinky after surgery and it is very tempting to bathe them!
First time Chihuahua owner with many years of dog experience!