Did that with an otter once. He was caught in a fishing line and a tree limb thrashing on the bank of a river. He had enough freedom to try to lunge and bite us, but we knew enough not to get close. Vicious little bastard. Pinned him with a stick and I stepped on his neck while my brother cut the line with a knife. Like 20 times. He was wrapped good. The last part was in between his claws. I really had to step hard on his neck and pin him with the stick after freeing all the other lines. That one arm was wrapped tight. He got away before all the line was cut off his arm, but there wasn't enough left to really slow him down. I'm sure it came off in the river.