Close fence gap?

[wimbly]

I have a small dog (7 lbs) and small outdoor patio. The old wood post fencing around the patio sits about 8 inches off the ground, just enough for the little guy to slip under. I was thinking that I could just use some wire fencing, staple it to the fencing and then stake it to the ground (below the fence is a bed of rocks, possibly some garden fabric underneath). Obvious, this is not a fancy backyard, and I don't want to spend alot (that's why I'm not replacing the fence). I just I want the dog to be on the patio and not be able to escape. Any recommendations on my idea? Better ways to do it? Recommendations for type of wire?

 

[Dekzion]

How about screwing another rail, or two, from post to post, roofing batten is long and cheap enough, put a drop of preservative on it and it's going to last at least 5years (more if you paint it every year)