We live in a very rural community. Zoning in our area is unheard of, really. I called to check the zoning yesterday, spent an hour on the phone with a confused clerk who had no idea that places have zones for such thing. *LOL*
In sections of my state that are zoned rural or farming, landowners can be required to fence their property. If a neighbor builds a fence separating his property from the neighbor, he can force the neighbor to pay for half of the fence.
I have no idea whether this is an unusual provision, but you might want to look into it if you're interested in building a fence. Get your neighbor to foot half the bill.