how does one recognize "fear aggression", as separate from other types of
aggression? and does it matter what causes the aggressive behavior?

Lola is no longer allowed to play with dogs who aren't Manu. i don't think
she's aggressive in the classic pit bull sense (going nuts at the sight of
another dog, unprovoked attacking, etc). but there's something going on
with her that i'm not ok with. see, she's really submissive. overly so.
her general reaction to a strange dog is to run up to them, crouch down,
lick their chin, then roll onto her back. this is all well and good, but
the older she gets, the more other dogs seem to find this behavior annoying,
and growl at her. this is what our neighbor's Lab does, he growls at her
and does some dominant posturing, and she just licks more frantically and
gets more wound up, crawling frantically on her belly, rolling onto her
back, then back to her tummy, and all the while licking their chin and
mouth.

yesterday, the neighbor kid was over with their lab, we were throwing balls
for the dogs to chase, and at one point, Lola did the submissive puppy
thing. Hershey started growling, and when she was on her back, he opened
his mouth and put it on her throat (not biting, just posturing). she
freaked out and did her "scary pit bull noise" thing that doesn't seem to
involve actual teeth on fur contact, but is scary to watch and isn't
allowed. i pulled her off, but not before she had received three wounds
requiring stitches, multiple small cuts, and was pink with blood.
the poor girl is has been trembling and whining since she came home from the
vet, and Manu has nearly licked her fur off trying to comfort her.

obviously the neighbor's dog is not coming over any more, and i won't be
letting Lola play with other dogs from now on.

but i'm still trying to figure out why she does that. she's so obnoxious
with the submissive posturing, we call it "aggressively submissive". what's
that all about? and when she suddenly fights back, is that fear aggression?
or is she suddenly remembering she's a pit bull? if it is fear based,
does that mean it's possible to train out? or should i not even bother,
based on her breed?

you know, as much as i love my dogs, and as much as i adore the breed, i'm
seriously considering getting pugs when they pass on.

-kelly