A lost Jack Russell showed up at our home and you can pet her and she's fine other times she will scream like your hurting her and she tries to bite you. Also, you can not touch her ears she will scream and try to bite. The vet said her ears are fine. I don't know if she encountered someone that was mean to her when she was searching for a home. She is a very smart dog and you can tell someone spent a lot of time with her and she's house broken. Maybe you can give me some reason why she acts like this.