It’s a metaphor. A loyal protector, got a brain disease, and turned on it’s family. The family had to put it down.
Think real hard. It’s a tough one. /s
Meh… GTH
It’s really an analogy you’re using, isn’t it? Rather than a metaphor?
In any event, now that you’ve clarified what you’te getting st, Yes!, the current FBI does resemble a rabid Old Yeller. And the end that Ild Yeller got is the same one the FBI should now receive.