White pus fillee bump on dogs tail

Hi vet, my dog has this bump unsure of when it started but it’s been a little while. A vet we no longer seee said it was a pimple and it’ll go away but it has gotten bigger and it goes bother her. I clean it often but I don’t bandage it up so it can breathe. As you can see from the picture there’s a hole there and thick white stuff comes out almost the same texture as a white head from acne except to me this doesn’t look like it.  Thanks in advance for your help !

Hello.  It sounds as though you have changed vet and the lump has also changed in appearance.  I wonder about the context, where this lump is as regards to the rest of the patient and whether it was the main focus of your consultation previously?  Either way, if lumps change, it is reccommended to have them reassessed.  This could be a small cyst or inflammatory reaction, perhaps centred around a hair follicle, demodex mite or tiny foreign body, which might help to explain the discharge.  However, it might also prove to be something more sinister so we would reccomend that you avoid handling the lesion and present it to your vet, who will assess it in context and propose a plan for investigation as needed.