How to get rid of annoying street cat?

we have about three cats in my street that are stray. people say a lady in the street owns them but she wont fess up. they are always around and i recently got a puppy. he goes off at night barking at these cats. i know it is them, during the day when they are barking i sneek a peak and they are sitting there. pity they arent scared of the dog yet. any suggestions on how to get rid of these cats from my backyard? and im not looking for an answers like call the local vet or buy a cage. i wanna scare them off with projectiles or maybe a foul smell or something like that. to give them a warning. if i hurt the cat it doesnt matter. just enough to scare it not injure it, relax cat people. any help appreciated