What specific security measure is suggested for fencing to thwart a Rat Terrier's attempts at digging out?

Answer

Adding a low-to-the-ground barrier or secure wire mesh extending outward along the bottom perimeter

To thwart early attempts at digging out, it is recommended to add a low-to-the-ground barrier or secure wire mesh extending a few inches outward along the bottom perimeter of existing fencing.

What specific security measure is suggested for fencing to thwart a Rat Terrier's attempts at digging out?
DogpestbreedcompanionRat Terrier