For a fact, ground changes. When I had goats, every gate was set at about 4 to 5 inches for inside pasture gates ( meaning inside perimeter fencing) . In the perimeter fencing may put closer to ground so dogs couldn't just slide under it. If we couldn't do it this way with natural land scape we box bled it so we could.,never lossef a goat to predator or dog except one time in 10+ years, and that one was a 5 month old baby goat had head thru the fence grazing and a guy came down the dirt road with 2 pit bull fighting dogs (I was told this later by sheriff department) when I reported the instant and that the dogs had caught lead poisoning from it. I saw where the dog owner tried tp load them back in the truck but couldn't catch them so he sped off before I got there. It was a shame as they where pretty dogs, but lead poisoning is very toxic. But they didn't get under gates.