Hhhhhhh, as Dave sort of pointed out - maybe forget what I said about lobes, and just go with the centre of earhole to earhole vs nipple to nipple.
That works for all animals (including humans), with nipples in a pair or pairs.
HTH. 👌
I bought an expensive little fret file from Crimson Guitars (I think it was). It has one smooth rounded edge so as not to damage fretboard or bindings. I also use it on my fingernails. 😗