What could this be - white hair tips?

[AthelstaneTheUnreadyFucker]

One of mine is black (ok, extremely dark tabby - you can only see the stripes in very bright sunshine and you know to look).

She used to be utterly black, but over the last 5 years has sprouted some white hairs in her ears, on the chest, and the belly. Just a few.

But now she has this strange patch about 2/3rds the way down her spine where the hair seems to be thinner and more brittle, and although there are some pure white hairs growing through, there are many more that are just white at the very tip. What on earth is this?

It's about the size and shape of two fingers' worth, it doesn't itch, she doesn't seem to be aware it's there. Could it be a fungal infection of some sort, or is it more likely to be mechanical trauma (repeatedly squeezing under something?). Either way, how does hair turn white at the tip, and not along the shaft?

Anyone with any previous experience?

it might be worth ringing your vet they might know never had this my ex husbands black cat was still very black the last time i saw him at 16 years old,

Ahh, thanks, Issey.

My general experience with the vets has been "we've no idea, it could be a skin thing, that'll be £60 please", so hoped it might actually be something quite common that other people had experienced.

If not, she'll have to go... cue wailing and vomiting and scratching and yowling...