My explanation is that there really isn't enough evidence to say exactly what happened to make her act that way. She could have hurt herself or got startled or something else.
I believe he showed that he has a collar which vibrates and demonstrated it on stream. It possible that the collar could also have a shock setting but that's not proof he uses it that way when training.
Since this article there have been no supporting eye witnesses and no reliable secondary sources supporting the shock claim. In fact, there is testamony of not shocking by eye witnesses and people who have first-hand experience with the situation.
So until there's reporting from reliable sources (with editorial oversight) or eye witness testamony it feels to me that it's a conspiracy theory.