Hissing at nothing?

Question
My cat has kept the entire house up the past few nights. She has always been skittish but never like this. She seems to be reacting to some threat, like there is another cat in the house. She gets her back up, hisses and growls. The problem is there is no other cat, there is nothing at all. She is hissing at thin air. I have had cats in the past but never encountered anything like this. Should I be concerned?

Answer
Charmaine,

This is the 2nd question like that in the past two days! Weird. Sometimes there is no explanation for what a cat sees or thinks he sees. Some say that a cat can see ghosts and spirits. I don't know if I believe that or not, but sometimes they sure act like they do.

Could she possibly see another cat out a window or some night wildlife though a window? Can she see her reflection in a glass door or window?

Another reason a cat acts like that is because it is in pain. Check for rubberbands on the cat, a sore area on her body, something caught in her fur that is poking her, etc. I would consider a trip to the vet for an exam if it continues.

Tabbi