Cat appeared on the back porch meowing at the door, would not go home after many hours despite the late time of night (1 am or later) and the cold. She appeared afraid and distressed and was preparing to sleep outside on the porch. On closer inspection she was a bit dirty, covered in painful thistle burrs and was ripping out her own fur to remove them. She also had no tags. Fearing that she may be lost and need medical attention, we left the door open and she entered. In the morning, we checked her at the vet for a microchip but she didn't have one. For the time being we're capable of caring for her until she's claimed.