You can lay down a defensive barrier using any canine urine.
The only problems would be getting the dog to go where you want, and getting a dog if you don't have one!
Dog feces has the same effect, but the prospect of dodging doggy land-mines can be a little daunting.
Heck, you could even relieve youself in the yard, but somehow I don't think the neighbors would appreciate you garden nuisance knowkedge as much as we would.
