While I dont know how the game stores the data I would guess from what you just said that it is acting as though it were an integer, otherwise the hundred times of pet healing should have eventually resulted in a raise.
Though I should note that healing pets only works if they are actually hurt, and hurting non-hostile monsters is chaotic. (If you didnt take this into account its possible you sabotaged your own efforts inadvertantly)
"you are the only cactus in the garden of my life" Gomez - Adams Family