I’ve seen it traced to “doglike.” But “Bitchy” does seem more apropos.
And yes, people can get pretty “damned” small and mean. Dogs are sometimes used as metaphors with a negative connotation in the bible (for example a group of people attacking someone who did nothing to deserve it).
Of course all generalizations are wrong :-). We are not speaking of the loyal dog who would die for his owner, etc.
Our problems come from sin, in classic Biblical and Christian understanding. God intended people to be caught up in His love, but He permitted a choice rather than turn them into puppets without a will.
When it dawns on a person that the Lord will fight on behalf of a loyal follower’s soul, even though he could not deserve it, a significant breakthrough has been made in the situation. This fight is what the cross of Christ is about.