The best I can figure it looks wartish? Never encountered this before, it showed up about 2-3 weeks ago as a small hard lump, and then over the last 1-2 weeks it got bigger, lost the hair and became all scaly and gross on the outside. It hasn't changed in about a week now. I assume I'll need a vet eventually to have it removed, but it would be nicer to coincide it with the spring teeth floating if possible!
These were the best pics I could get, my camera sucks and Jynx is like a 3 year old with ADHD.
I might be totally off here, but from the size shown, could it be a tick that buried its way in?
No, I think that would be impossible due to how cold it is here. Ticks haven't been around since August at the latest, and actually they didn't get ANY ticks this summer from where they were pastured (no grass or trees in vicinity).
It really just looks a bit like a wart, but I haven't had a lot of experience with warts!
I would think, as long as it stays as it is now, it can probably wait for the spring vet visit. But if it started changing size, shape, or color further, or got in the way of her halter/bridle, started bleeding or seeping, etc. I would probably suggest calling the vet in sooner.
Last year, I rode a horse that had similar bumps pop up out of nowhere. They were located on his face, back and barrel. They would start off as a hard small lump under the coat, then would grow and scab over and as a result would loose the hair on that spot. The vet diagnosed it as 'Protein Bumps'. They were resolved with a minor change in his diet. I'm not sure if they would occur in a 3 year old or not (my horse was 22 at the time), but maybe something to look into.
Good luck, and please let us know how you make out.