We have a staffie who caused us many an anxieties until we fenced a large portion of our garden with chestnut paling fixed firmly to posts. The hedge grows through it eventually so it becomes invisible.
The beauty of this type of barrier is that as long as it is well fixed every 6-8 feet, even a determined dog cannot push it up & escape underneath. Staffies are incredibly strong around the head , neck & shoulders & can usually barge it's way through anything, but this has worked incredibly well for us. It is'nt expensive either.
Hope this helps, good luck, Ann.