Before thinking of a dog, consider what a car thief told a friend. yes, a dog will keep us out, but, can he put out fires? Some people will destroy the protected item in revenge.5 months ago I had thieves break into my workshop with an angle grinder. They couldn't take the bike as it was on axle stands with the rear axle off and in pieces. So they put the axle grinder through the ignition barrel out of spite.
I've a special dog sleeps in the workshop now.