An E collar was used on my rescue GSD for being mouthy with strangers (by previous owners). It backfired badly, I believe he now equates meeting new people with a shock and occasionally snaps, instead of mouthy puppy play. I am working hard to rehab him) Just an example of what can happen . . .
Until we meet again . . .
Bear(rescue)-GSD, my soul mate.
Kai-(rescue)GSD, my forever baby.
Kobie-Pomeranian, my tiniest dog with the biggest heart.