I read that book back when it was first out in paperback, plus many other true crime novels. I was heavily into them in the 80s & 90s. Hers was one of the best IMO.
We've trained Akitas for over 3 decades now, and one thing you learn about big dogs is never let them think they're alpha. Some of our males we've had to 'take down' on their first aggressive behavior, others have never tried. Once they've been shown who's boss they will behave cowed for some time, unless the alpha takes steps to soothe them.
I'd be curious if they were male dogs, then I'd say just normal canine behavior. Bundy probably abused them at some point.