Assessing Aggression Thresholds in Dogs: Using the Assess-A-Pet Protocol to Better Understand Aggression

I agree that a trainer will be necessary, but more specifically, a good method to look for for this issue with be Threshold Training, also called Behavior Adjustment Training, BAT or even just Desensitization. You'll need to educate yourself about techniques IN ADDITION to working with a trainer, so don't consider this an alternative! But Behavior Adjustment Training 2.0 and/or Assessing Aggression Thresholds in Dogs can help you learn your way around these techniques. And please don't worry about being embarrassed about a muzzle - you need to worry about your dog being put down if you don't give her protection from her own impulses. Kikopup is a great training source in general, and they have a video about muzzle fitting and training here And finally, there's an entire sub about this issue at r/reactivedogs/