There's some stuff called "doggy no". You can spray that on your patio.
If you want your dog to go in one spot there is a stake you can buy! You hammer it into the ground and it attracts them to it and they will go there and do there business.
We have 2 alaskan malamutes. The female is very lazy by nature, and has started this some years back because she does not want to step in the wet grass. Now it has become an every day thing-dry grass or not. Not good for entertaining, plus it is an everyday nuisance. Help!!
You can put pepper on the patio or orange peels. Or you can use sprays which you can get from most pet shops. Hope this helps x