New user here been a lazy leecher decided to donate and help out. A recent bug that was posted (couldn't find old thread) detailed on hunters turning aspect of the hawk on and off to bug/reset pet hp bar. It still works but further looking into it, its not the act of aspect changing that resets it, but changing your own stats.
For some reason as BM - unequipping weapons and re-equipping costs a GCD
as SV it does NOT.
So far soloing heroics with it I've managed to come up with a way to equip/unequip while fighting, but I imagine it is possible to make a macro to use shots and weapon swap (can change weapons in combat) to perma bug pet hp to infinite as you fight.
TL'DR swap weapons/change stats in combat to make pet unkillable.
Edit: in battlegrounds I've manged to keep pet alive at all times no matter how many players attack it, dueling as well by merely weapon swaping.
There seems to be a no return point (pet 1-10%ish) where it will no reset his health meter to full in PVE though. as for soloing heroics/other content as long as you keep weapon swapping pet will stay unlimited HP (works great with MD Glyph SV AOE, I'm using a beetle atm from silithus http://www.wowhead.com/npc=11726) to avoid any instant gibs from large pulls.
If anyone could come up with a macro to weapon swap tied to shots, perhaps you could mash it and take it further ( was intending to use this trick to solo whale shark at cata release) Thanks!