Dog yard is not dog proof

I have come to the conclusion that it is impossible to keep dogs contained with anything less than an eight foot tall fence.

I have raised the sides of my dog fence to 5 feet, and BB and Bear don't even notice I raised it an inch, they sail straight over it. I can't blame them, they're good size dogs and I have only been able to hobble together the things to fence off about twenty foot by twenty foot of the front yard, but still. It is highly annoying to have them just leap over it.

I need to finish buying my 6 foot fencing boards (only $400 to go), and get the yard fully fenced in them. My theory is if I can put them up on a two foot tall concrete footer, then I can deter the dogs from escaping the yard. And since two sides of it already have a cinder block retaining wall for the dirt when I put in the lawn, I just have to bury a row of cinder blocks along the third side (fourth is against the house) and they won't be able to dig out under it either.

Just need to get together the funds for the project.