Dear folks at the MoMA design store in Soho: my online dictionary has this definition of “curb”: verb:to cause to keep near the curb: Curb your dog.
and this one: noun:a rim, esp. of joined stones or concrete, along a street or roadway, forming an edge for a sidewalk.
So there is no example of the second definition next to your building.
If you want dogs to shit and piss elsewhere, you should just say so. If you want people to follow the first definition, no further embellishment is needed.
Sorry to be pedantic, but you did waste a lot of money getting all those new signs made up special.