My dog is making progress, but…

I have a very reactive heeler who wasn’t socialized as a baby prior to adoption. Her level of aggression is rather extreme. She’s really murderous it’s not just reactive fear. She is dangerous to other animals and must be muzzled so as not to kill other dogs and cats. I do not expect her to ever be able to be around cats but I also see very few success stories with dogs this agressive ever being safe around other dogs. Posting in hopes we aggressive dog owners can trade some tips or success stories . She is difficult to train at all outdoors as she completely loses it if a dog is even far away and tries to pull off her muzzle etc. she will bite you only if another dog is present otherwise she is a codependent little coyote.