I routinely clean my mares teats (unsure of the technical term, but I'm sure ya get it I had noticed a pea size hard bump on the inside of one and isn't causing her any discomfort, but has a strange hole on the top. No discharge and has been roughly a week or two since I noticed.

For the meantime I'm just keeping it clean as I can. Does it warrant a vet visit? Any ideas? Thanks!