When I was a young adult, I had to fight off a mad dog. A German Shepard. He came at my throat. I shoved my forearm into his mouth. Got him on the ground. Beat him senseless. He was bleeding from the mouth, nose, and ears.
The dog gave me 13 stitches and my mother 9. A costly trip to ER. It could have been much worse. We survived. The dog was euthanized.
From that day, I knew that if I had to defend myself against a large animal, like a dog, I would shove my hand down it's throat.
There are a few other techniques.
Become the kind of person that when your feet hit the floor in the morning, Satan groans and says, "OH NO, HE'S AWAKE".