Dog's skin is going black - any ideas?

[OpenWheelRace]

Our Border Collie (12 years old) got a nasty flea bite on her back late last year which she kept chewing and scratching at - it got infected and the vet shaved a strip of her fur to clear all the gungy fur and gave us an anti-inflammatory spray to apply to calm it down.

The fur still hasn't grown back (it's been about 4 months) and I've noticed that a patch of the skin has actually gone black.

She's not bothered by it at all, never bites it since the infection went and doesn't scratch there.

Does anyone have any idea of what it could be? Should I be worried?

The vet will charge us £40 for a telephone consultation - I know because I paid for one a couple of weeks ago (for something that turned out to be nothing!) so I'm a little wary to jump straight into vet appointments.

[Veterinari]

It needs to be investigated. I'd be concerned that it was never a flea but but could be the start of a skin tumour...

[OpenWheelRace]

@Veterinari

Ok. I'll book a vet appointment for Monday.
The flea explanation did seem strange at the time because we were regularly applying Frontline. The vet said that was no longer the recommended flea treatment and we give her Bravecto now.

[Veterinari]

Yes that's true but I don't think this is just a flea reaction - def worth a biopsy

Can you email the vet the photos ahead of the consult ?

[OpenWheelRace]

I'll email them over and see what they think - I really hope its nothing serious.
We haven't had her a year yet and she's set us back thousands. I love her to bits so I'll pay what it takes but even so

[OpenWheelRace]

The skin is completely smooth to the touch and its not raised or a lump or anything

[Veterinari]

Ok that's good, usually we'd only see colour change if there's been chronic irritation or if there's underlying pathology. Best to get it checked anyway