From petting to hissing??

Hi all. I have a question about one of my cats.
She is a very pretty short hair domestic. I got her about 4 months ago I found her stranded on a snowbank and ended up taking her in and keeping her. (I did look for the owners)

Okay so she is about 1 year and 2 months old, she is not fixed yet. but has been tested for Feline Luekima, it was negative, has her distemper and rabies.

SHe is a good girl but I don't understand one of her behaviors.

When you pet her she will lay on the floor looking relaxed but then all of a sudden will swat at you and hiss. Now i have figured out that you can't come up behind her and pet her, she jumps when you do this. Also If you go to pet her you must put your hand in front of her face so she can sniff your hand, like you would do with a dog.

The thing is to, if you lay on the bed with her, she will cuddle right up with you and has no problem being petted. I don't know if she feels threatened when your not at the same level as her or what.

What do I do if she hisses while just being petted?? I just don't understand why she goes from relaxed to hissing.

Anyone??

I think this is a very common cat behavior. The swatting and hissing is just to tell you they've had enough. Some cats will put a paw on your hand first. (I've also heard that they get sexually excited by petting and hence the transformation of behavior - maybe someone here knows more about that, and if it's true or not.)

One of my cats, like yours, loves being petted for a long time only if I'm lying down. I think it's because I'm in the submissive position then and he feels safe. (Overall, his personality is pretty skittish.)

The thing to do when she hisses while being petted is just stop. That's what she's telling you to do.

Are her vision and hearing normal? It sounds like she may have petting overstimulation agression, but if she spooks easily from behind, she may be deaf.

A lot of cats will become overstimulated very easily, its normal. I give a little hiss back, not big or overdone, just to let them know that I am still the alpha, and then act like nothing happened.
I would check into the deafness issue though is she is very easlly startled. Also could be that she was treated not so nice wherever she was before you found her and is just reacting to a percieved threat to her safty.

ETA: My cat is still, after 2 years, skittish if I move too fast when reaching to pet her. She also doesn't like being approached from behind, though definatly not deaf (she can hear a snack bag crinkle form a dead sleep 3 rooms away) She was in a bad home before I got her. I just take it slow, and look for the warning signs when petting her, ears flattning back, eyes getting a bit squinty, tail twitching fast.

Thanks everyone, deafness is probably not the issue I know she can hear me when I call her, or when the birds chirp at the window.

I wonder what kind of home she came from or how long she was outside before i found her, although her coat was in good condition.

She might have been put out, a lot of people think that is OK, that being cats they will survive. She might have got loose and couldn't find her way back, many things could have happened. If she was living outside she will be naturaly cautious. Just keep on what you are doing, let her smell you, and approach from the front.
Avoid looking her directly in the eyes if you are petting her that can be seen as a threat to cats.