well, if u cannot confirm, it's not certain evidence
maybe from WoL if you use the expression editor box at the left side and go to the damage done tab and enter: target = "Venomous Head" or something? You will need to know how uch they killed it though, I cannot check it at work as it's blocked, but a nerf from 45M to 28M is huge.
But that isnt my question, I would like to know if the HP pool of the body is reduced aswell? atm its 315M. If its 37M/head it should be 259M for the body.
28M would be 196M and that would be too much imho.