Well I have a little experience in this area since we used to run cattle and hunt on a couple of hundred acres that was surrounded by houses and subdivisions. My father and I had a couple of simple rules.

1. Any dog under 15 to 20 pounds was usually pretty safe(unless it was constantly in the pasture ie see it 10-15 times a month).
2. If we saw the larger dog in our pasture more than 2 or 3 times we shot it.

Reason - Dogs will pull down a young calf and since I have a fence to keep my cattle in you should have a fence to keep your dog in. When the dog being out starts to become a habit we took care of it. A couple of times some small mutt dogs were constantly in the pasture so we eventually took care of them as well. We would give them a chance but repeat appearances in the pasture meant they were dead dogs.

I have an English bulldog that sleeps with us and is a member of the family, but that is why I keep him in a fence. It is amazing that people move out to the edge of the country and think their animals can just run free. JMO

Later
Gone_Huntin