speaking from experience as i was once attacked by a big German Shepard, it was my own dog in my own house, turns out if had a brain tumour and just went berserk.
i always thought i would be able to fight a dog off, but with a good sized powerful dog its harder than you think, they are so fast and aggressive, and what you think you would do goes out of the window whilst your under attack, my dog got hold of my right hand full on and was ragging it around, i didnt want to pull to hard through feel of losing fingers, i pulled it to my left so i could rain down punches to its head, all the while not actually wanting to hurt my own dog, i managed to get it off eventually, only for it to leap back at me and grab hold of the back of my leg, luckily it eventually got pulled off me,
ended up with a finger end hanging off, broken in 2 places and a hole in my had i could see through, and about 100 stitched in my leg, finger has never been right since and this was over 20 years ago, it was bent and had no feeling in it, and it the cold it felt like it had been smashed with a hammer,
now i know what some dogs are capable of, when i walk my dog which is a giant schnoodle i always take my walking stick which is a twisted knob stick, and because of the places i walk are all across farm land that i have shooting on, with public rights of way on, i always carry my hunting knife on my belt, so first any unruly dogs get shouted at, then it will be a jab with my stick, then its a good crack if then intent on danger ring me or my dog, and if i feel the need as a last resort its getting opened up,