Update

Right now, Kimmy is still with us, and we're both (my husband and I) at a loss, really. I've been practicing the Nothing in Life is Free tactic with Kimmy and I can see (objectively, I hope) certain changes in her demeanor.

We've been also practicing "bicycle situations". To let her know that it's unacceptable to run after or even try to attack a bicycle in motion. Which she obviously has the instinct to do.

I must say, last night as we went for a walk, we stopped at a neighbour to say hi, and let Kimmy play with their labrador for a bit (off leash), and then we saw a bicyclist passing. Kimmy stood there, in her "alert" stance, watching the bicyclist intently for a couple of seconds, while I growled in a low voice "Noooo", and she turned to me and laid down. Yessss!