I live on an urban lot (about 7000 sq feet or so) with a fenced back yard (I think it is probably 40 x 60 feet). The fence is a typical privacy fence, so I guess 6 feet tall?. The two gates are 4 feet tall. My chickens free range back there, they have never attempted to leave the yard. The house next door is for sale. A couple that is interested in it have a large yellow lab. The first thing I asked when I met them was if they had a dog, they knew I have chickens, but they assumed I was concerned about barking. I am concerned about the dog jumping the gates or fence. I know little about dogs, can big dogs jump that high? Do dogs tend to dig under fences? How worried exactly do I need to be? Most people think their dogs would never hurt a chicken, they didn't take me seriously when I said I was concerned. Sort of laughed. (Perfectly nice people, btw). My husband also is not taking me seriously. I will not tolerate my chickens being bothered by a big dog.