In most cases, yes. But LGDs have been killed here, too. It's very rare, though. And maybe those LGDs weren't well trained.If LGD is fit for the job and in enough numbers then mountain lions do not risk their livelihood to hunt in risky situation.
Predators think long term survival and they avoid being hurt and injured at all cost since they can't go to vet to right the wrong but LGDs have their masters to go to leak their wounds.
Ps: I have no problem with shooting predators that has been habituated to homestead easy meal.
Who am I to judge how you defend your livestock in your county?
It does not make me feel happy though to see foxes are dead, chickens are dead and a frustrated homesteader lost chickens ( financial and mental pressure) when maybe LGD can be the solution. I mean permanent solution . Because shooting predators is normally not the long term solution but just a pain killer with limited efficiency .