A properly constructed 5½- to 6-foot mesh wire fence should have horizontal spacing of less than 6 inches and vertical spacing of 2 to 3 inches. It should have barbed wire at ground level and barbed wire, electric wire, or wire overhangs on top to help deter predators that will climb or dig under fences.
Multiple strands of single-wire electric fencing can cost less than new mesh fencing. Seven or nine strands of high-tensile smooth wire, with alternating charged and grounded wires (beginning with a charged bottom wire) can help reduce predation.
Adding electric wires at the top and electric trip wires to the bottom and middle of a mesh fence that is in good condition can help make it an effective predator barrier and is probably more cost effective than replacement. An electric trip wire placed about 6 inches off the ground and 8 inches outside the woven wire fence will help prevent predators from digging under it. Electric wires added to the top and at various intervals along the woven wire fence will help discourage predators from climbing or jumping the fence.