dogs usually exhibit traits they inherited from wolves (like being pack animals).
It shouldn't be a surprise. Chickens retain most of the instincts they inherited from jungle fowl. i.e. roosting, scratching for food, the egg song, wariness of motion from above, etc..
Growing up, my parents had a farm but I lived in the city and we had huge packs of dogs that would run the streets at night, sleeping in parks, cemetaries and drain pipes. I was driving down a city street about 3AM and about 20 dogs attacked my car. I'm glad I wasn't walking.
As far as I know packs of feral dogs are still a big problem in some cities. Twice in the 80's a dog pack got into the St. Louis zoo and killed antelope. Once they wiped out the whole herd of Springbok.
Edited for spelling