You can only change your neighbor's fence with their permission. A neighbor's fence is their property, and altering it without their consent could constitute trespassing or property damage, which may have legal consequences. If you have concerns or disagreements about your neighbor's fence, communicate with them openly and try to reach a mutually agreeable solution. If you believe the fence violates local zoning laws or property regulations, consult with local authorities or seek legal advice to address the issue through proper channels. 

The best under-gate dog barrier is one that extends to the ground. This effectively keeps dogs in and won't give them room to squeeze through. However, dogs that dig can still get under the barrier. Deter digging by paving the ground beneath the gate or filling it in with rocks or gravel. Be careful using wire to extend dog gates, as the sharp ends may cut or hurt your dog's paws.

Since wood is weaker when installed horizontally versus vertically, a horizontal fence is prone to sagging. You can prevent this drooping from happening by building a sturdier fence. Use softwoods that are more stable, such as cedar and redwood, or denser hardwoods for your fence materials. If you can’t afford these pricey materials, use thicker two-by-six pressure-treated pine boards or shorten the span the fence boards have to cover by installing more posts.

Regular maintenance for wire fencing includes annual inspections for rust or damage, tension adjustments every two to three years, and immediate repair of any breaks or loose sections. You should also regularly check the fence posts for stability, particularly after severe weather, and make sure to remove any vegetation growing along the fence line.