cat butt and tail shaking

by Julie
(PA, USA)

Sometimes at random my female cat will - while standing - puff up her back and shake her butt with her tail up in the air, as if stretching but shaking/vibrating at the same time.

My uncle said she was trying to spray, but she never urinates when she does it.

What is she really doing? She's otherwise healthy though she has chronic allergies and sneezes a lot. (eats, poops and has normal activity)

Thanks so much!

Answer by Kate
well to me this could be just the way she stretches. My own cat does something similar from time to time.
The other option is that she may have a parasite like worms etc. It might be an idea to have her checked out in that area, just in case.

I wouldn't worry too much in general if she is generally healthy in all other ways.

best wishes Kate