Beware the Invisible Fence

They've been out for a while now -- the invisible fences to keep dogs contained in a yard.

A friend was surprised with how well it worked. She told me how it didn't take the neighbor's cat long to figured out just where the boundry was. The cat would sit just a foot or two from the invisible line, licking herself, as her next-door neighbor cannine jumped around, barking and yapping at her. Only, one day, my friend let out the dog before turning on the fence, or forgetting to turn it on. The cat was cool as always. The dog stopped at the invisible line and barked. The cat continued to lick and tease. Then the dog took a few steps forward, and a few more, then started after the cat, who stopped mid-lick to save her teasing hide.