Liz Buchanan BVSc MRCVS
Hello! Interestingly, like human warts, dog warts are often viral. They are caused by Papilloma virus and can be associated with low immunity - for instance in young, old or ill animals. Warts can look distinctly different from one another but your vet should have a good idea: all new lumps should obviously be presented to them. If your vet agrees that this is a wart, then they may opt to wait for a while before attempting any kind of treatment as many warts do self resolve within a few months. They may also suggest precautions regarding transmission (to other dogs - not to humans).
If a wart is continually getting scratched or scraped or made to bleed, then early removal can be indicated. This does involve a general anaesthetic. It is also worth asking whether, on any particular timescale, they might want to resee you if the lump is still there.
You don't say how old your dog is now, but other clinical signs that might have caused a dip in immunity might also be picked up on clinical exam.
Please do let us know what happens!