MY security is pretty much like Steves. Only mine is a Jack Russel that HATES cats in the garden and thinks every single noise from outside the back door is a cat.
3 times in the past 18 months his teeth have missed kids/folks by milimetres as they run from the trees and jump over the fence. When he goes to raising hell at the back door i know i know it's time to let him lead the way and i'm comiong in behind as backup.
Incidently Steve, The theives around my way are as likely to take that dogs of yours as any tree.
