Is this always a fearful behaviour?
My dog will, if I ask her to, lie down quietly when the vacuum is on and will be perfectly relaxed, not tense or eyeballing the vacuum or anything but if not specifically asked to lie down quietly she is a nightmare when it is on!
She will follow me around, sometimes making a sort of moany whiney growly sound and if the vacuum comes close enough she’ll bite it.
I assumed it was play, just wanting to bite the vacuum but it’s very annoying hence her being asked to lie down and my friend (experienced dog owner) laughed when she saw it and also thinks it’s play.
But, I deliberately filmed her just now and actually, I think she looks scared.
I’ve tried uploading the video but it seems that only photographs come up in photo library