He is a sweetheart but the way he barks and can show off his teeth and then demonstrates his speed "chasing" the loud trucks and motorcyles (races them along the fence line I have about 500 yards of street frontage) as they go from one speed bump to the other speed bump in front of my property.

He is well trained and will not leave out the front gate without one of us present. So the other day gate is open and mailman arrives in his jeep. D'Artagnan goes ballistic with his usual show. Stands on about 10 feet away from mailman on our side of the fence 5 feet one side the rolling gate is wide open. He doesn't go around and outside to get the it but stays in his spot going ballistic. Mailman had a bunch of packages so he honks I walk outside go get the mail. Dog calms down but stays alert still on our side of the fence. Even when I cross the fenceline he stays (Because he is not allowed to leave without being called or directed)

As a kid I was bitten by a dog while riding my bike. If a dog is loose not on his property by all means Pepper spray is an appropriate response.