I got a 10 year old lab from a family with 2 kids (both in elementary school).
They had his brother (same litter) and after 10 years, decided to give only one away and keep the other. Their reason "He jumped 6 ft walls to escape out of our backyard."
I had a black lab that did that. He wouldn't clear the fence but could get high enough to get his head, front legs, and shoulders over, and then he would scramble the rest of the way.
I fixed his wagon by installing a hot wire on the top of the fence. Only took one time.