The idea that a dog is going to stop a burglar only shows a real lack of experience in the security industry
Unless the dog is trained to only eat on command you are really putting the dog at risk of the poisoned meat through the letterbox and before anyone dismisses it I do have real life experience of it happening , if you can't train the dog to eat on command then you then need to consider different letterbox arrangements i.e. external box and block up the existing one at the door. I know of a number of cases where the "guard" dog has been poisoned and subsquently died while the premises was burgled going back to the 80's, I know of a couple of cases where the dog was trained to eat on command and waited for the breakin and the best one was a dog a mate of my dad's owned he stayed silent while a guy climbed through one of top opening windows in a downstairs room and when his feet touched the ground the dog bit his rear end and he left the same way taking his injured rear with him as he came in leaving a piece of his trousers in the dogs mouth a little while later when he came home from work the dog greeted him with the evidence and after a phone call to the police they took the evidence and arrested a man at one of the local hospitals who was getting treated who was missing the exact same piece of his trousers
With CCTV I sometimes find it is better to install more covert cameras and install visible dummy cameras or a mix of visible working and dummy cameras to catch out any thieves that may be prowling
In the past I have done a lot covert CCTV work and there where quite a number of convictions based on the video evidence I captured which is why I favour the covert method as you capture more when those who are prowling have their guard down and think you can't see them