Just to give you an idea what a determined dog is capable of, have a look at this videoclip:
http://www.clipfish.de/video/2700006/flucht-aus-dem-kfig/15

Had me And some people wonder how a dog gets past a simple garden fence....

OMG that is incredible and the other beaglies "don't leave us here, open the dooooooor" doesn't look like a very nice place to live though, no wonder he wanted to escape

Although I have to say he can't be very happy in there to go to such desperate measures to want to get out Aren't they crafty!

Clever little tinker or what!

Errrrr yes ......... I used to have 2 Beagles and they were always escaping 6 ft high pens couldn't hold them and they always ended up in the Rosyth MOD guardroom with the GSD guard dogs sharing their treats/biscuits!

My parents first dog a springer x lab (Sandy) could scale 7ft, no jumping involved just used to climb it Her favourite place to be would be on the flat garage roof waiting for the postie or any passers by, she was the hardest dog anyone could of handled looking back now I don't know how they managed her. My father used to take her dummy launching at an old quarry she once landed on an upturned broken glass bottle that went straight through her paw but would not get back in the car as she had not had her "hour" out.