I'm not sure...
My neighbour has a large dog. It frequently jumped into my garden as a puppy and so she made the fence between our gardens taller (from 3ft to 5ft) to stop the dog jumping it. However, the dog still jumped it.
Then she fenced off part of her garden, also with a 5ft fence, so the dog has a seperate part of the garden to her children and they can play undisturbed. So, the do ghas to jump both 5ft fences to get into my garden. The dog can and does still jump both fences. Within seconds of being let out. Every single time.
So, she resorted to tying the dog up on a long line whenever it is outside, to stop it jumping over. Dog can no longer get into my garden.
However, in the last month or so, since I have had chickens, the dog has jumped into my garden twice. Today when it happened I was very luckily in the garden and managed to grab the dog by the collar as it opened it's jaws to grab one of my hens! I think it may have made slight contact, but the hen seems OK.
I would be devastaed if the dog killed one of my hens, as would my children. They are pets. I'm thinking of asking the neighbour to put a strand of electric wire on top of the dividing fence to hopefully be an 'emergency' fail safe to stop the dog jumping into my garden if it should ever get out/be let out without being tied up. Is this unreasonable?