If you purchase close to town, the best place for doggie recreation is the Stowe Quiet Path, which is off-leash except for the parking lots and when on RecPath sections. Fresh water, open fields, away from traffic, and opportunities for well-behaved friendly dogs to socialize make it a favorite for residents and visitors alike.
Even if a condo is pet friendly, I can't see off-leash being the norm. StonyBrook has walking trails behind the property that are off leash. It also abuts the RecPath.
Here is list of condos