Check around to see if you can find who makes those stockade fences, vinyl or wood. Is there a factory outlet or salvage store nearby?
Would a solar fence charger work? How'bout that old mountain solution, shotgun shells loaded with rock salt, in their faces?
You can't butcher the darned things, but do you happen to know some bad boys with freezers who can do it while you're out of town?
Last resort is the pellet gun, poisoned or otherwise, aimed squarely and accurately up the anus.