Liz Buchanan BVSc MRCVS
Hi - this could be a wart, and warts can be viral. There is a great article in the blog called something along the lines of - Why does my dog have a wart?' which is worth a read. I might wonder, if an apparently healthy 6 year old dog has developed a wart, whether there may be an underlying reason connected to a dip in immunity, for example. Other possibilities include things like cysts, clogged follicles or tumours (you can read us saying througout the blog that its hard to identify lumps just by looking and we wouldnt assume to do that over the net) so it can definitely prove worthwhile chatting it over with your vet.