Dog Head Shadow

I went to the bathroom this morning, around 11, and I was at the bathroom sink and looked over at the bathroom window and through the curtain I seen a shadow of a head that looked like a dog's head. it was about medium in size and was there for only a few seconds. Our bathroom is on the second floor and there is nothing outside of it to cast that kind of shadow or even any kind of shadow at all. It was also a really dark shadow.