We have had to install new fencing to keep the lurcher in as he can jump like an athelete. He has done so on many occasions so far to keep joggers company.
The fencing is made of 2"x2" posts fitted to the top of the wall using anodised steel brackets, with 1.5"x.75" batten rails between. We have fitted upright battens at 6" intervals to make it like trellis. That should keep him in. It is designed to be non destructive, so that we can take it down in the future without damaging the wall.