We have a dog who will be 1 in a few weeks. She’s been toilet trained reliably since probably 4 months old. Not a single accident in the house since. Tonight we left her downstairs to roam around while we bathed the kids. All the backdoors were open so she could go out whenever she liked. When we came downstairs she had done a massive wee on the sofa. Could this be a sign she’s going into heat? She’s not had a season yet. It wasn’t a small amount of urine marking, more a massive patch of wee. I’ve only had male dogs before.