We collected 2 9 wk old girl pigs from a local rescue centre on Monday. They have seemed to settle in fine, if very shy. DD adores them. Putting them out in the run today I noticed one had a sore spot on her back. I've shown it next to my fingertip for scale. I've not seen it before - it's not raw and looks like it's healed over but there is no hair growing there. She is long haired and quite tufty so not sure if she had this from the start or not? What do you think it is? Do I need to take her to the vet?