I would just let the cat stay in one room for right now. Don't try to touch her
or get near her. Give her time to calm down. You could also try some catnip.
Just put it on the rug. Hopefully she'll like it. That's how I tamed my once
feral like cat. You could also try some valium to relax her while she gets used
to her new surrounding. There is also "rescue remedy" and "feliway" that might
calm her down. Sounds like she's scared half to death. Good luck.

Joan,
I've never encountered a cat like that, but I heard that some cats are just
vicious for no obvious explanation.  This is rare, but can happen. Sometimes
it is temporary.
It's possible that your cat is reacting to the stress of the move, but that
reaction seems extreme to me.
If you have not already done so, you should find out more about this cat's
behavioral and medical background.  See if you can find out if she has
always been this way and if not, when and under what conditions did it
start. Bear in mind that some cats who are perfectly fine at home can be
holy terrors at the vet's, but this cat might have a medical condition,
brain tumor, something that causes the vicious behavior.
Also, think about your own environment.  Maybe the cat smelled a strange cat
or some perfume or cleaning product odor that set her off.
If it continues or is the cat's usual behavior, she may be a danger to the
other cat as well as to you.
Depending on what you find out and given your own medical condition, you may
be able rehome the cat, maybe as a barn cat.  Or, sadly, you may have to
euthanize her if she can't be helped.
Meanwhile, Feliway spray (not on the cat, but in the environment) may help
some. Keep the cat isolated in a quiet area.  Wear leather gloves and long
sleeves and long pants if you need to go in to feed or clean the litter box,
etc.
By-the-way, there are safer alternatives to flea collars.  You might ask the
vet for a recommendation.
Good luck.  You are kind to take these cats in.  It was very unfair if the
previous owner knowingly kept from you information that you need to know
about this cat's behavior.
Annie

I don't mean to sound brusque, Joan, but first get rid of the flea collar. They
are toxic, most of them not effective anyway, and it's just one more thing to
stress the cat if she's not used to a collar. Try Advantage, Frontline or
something.
This is just anecodotal, but my son's cat sounds just like your hell cat. I've
had to babysit him on occasion, and sometimes all you have to do is pet him and
he acts viciously. I found out he's okay if I totally ignore him. I don't even
act like I see him. I've only kept him for a few days at a time, so I don't
know if that approach continued would eventually settle him down. I also have
to keep him separated from all other cats, because that sets him off too.
In your case, though, I can't help wondering if there's a medical issue and the
cat's in pain or something. Although there *are* some cats that are just highly
agressive, it's certainly not normal for them to be.

here,  bloody-hurt-- and oh so sad.

I just wanted to say that I am really sorry the cat hurt your mother and
that you are getting all of this grief instead of the joy that rescuing cats
can bring. You clearly are a loving, good cat mom and you deserve better. I
have never dealt with a truly vicious animan--just a REALLY MEAN one that
loved me and so usually pulled her "punches," so to speak. I imagine it
feels like a slap in the face. Poor kitty, too, who knows what she has been
through to make her that way. I agree with you that she should not be let
out if you live in an area where cars travel through. If you must rehome her
as a barncat via a shelter, or even if you must return her to a death
sentence, you cannot risk injury to you, your mother, or your other loved
ones. I hope someone here can help you to find a solution.

Maybe she wasn't - with her owner.
You are a stranger. No matter how long you've had her, until she trusts you,
you're a stranger.

Haven't met my Rowan. *g*
Lovely cat. To me.
Has big red letters that say I BITE on her vet chart.

Why?
Round up from where?
Did she corner a terrified cat and expect it not to lash out?

Let her out where? Outside, or out of a room?
Where was she?

Why did she need to go "back inside"?
Did she get outside the house?

Again, why a collar?
The neck is the most sensitive thing for an animal. Many animals will bite if
you touch their necks if they don't know and trust you. Grabbing a cat by the
scruff or any part of the neck is either dominance, discipline, or an attack
to their way of thinking. Only ultra-domesticated and VERY trusting cats will
quietly allow a strange, non-trusted human to handle them and put something
around their neck.
Think about what you are doing - from the cat's POV.

A few fleas on her is preferable to destroying your chance at earning her
trust. Leave off the meds she doesn't absolutely HAVE to have (all,
hopefully) until she trusts you. Handling her roughly, which I assume must be
done to subdue her to medicate her, would reduce her trust even more.

Have you left her alone?

We need a lot more info here to really be of help.
How long has she been with you?
How old is she?
Where does she usually stay? (in a room, outside, in the basement, huddled in
a favorite corner...?)
Have you given her time to adjust by just leaving her alone and letting her
come to you? Or have you always tried to approach her?

Many cats don't like or trust strangers. My girls would have a fit if I
dumped them at a strange house and then the human there tried to pick them
up. My boy Jeffrey would be scared, but probably love you anyway. Rowan would
flay you to pieces with teeth and claws. Isis would flay you accidentally as
she tried to flee out of your arms, but probably wouldn't hurt you on
purpose.

Is there some reason you feel the need to approach her? Why can't she live
with you, free from being approached at all until such time as she chooses to
initiate it? I don't know enough about your situation to know these answers,
so please give us more details. As much as you can. The more you tell us, the
more we can help.

In the meantime, a few helpful hints on how to get my Rowan to allow you (a
stranger) to touch her, in the hopes that it might give you some insight with
your new girl.
1. Don't ever move towards her. Let her come sniff you. It may take awhile.
Like, hours. If you move towards her, you're done for the day. She'll take
off and go hide and won't come out until you're gone.
2. Don't look right in her eyes.
3. Don't talk loudly, don't move suddenly.
4. Don't EVER try to pick her up or restrain her in any way.
5. DO offer her food.  :)
6. When offering food, toss it in her general direction, but not AT her.
Don't expect her to take it from you. She won't.
7. DO speak softly and in a higher-than-normal tone of voice to her, much
like you would to an infant. Kissy noises optional. *grin*
8. DO bring out the flashy kitty ribbon toy, but don't try to grab her as
soon as she decides it's okay to play with it. Just play and then leave her
be. Don't try to touch her right away.

It took my Mom 4 hours to get the cat to sniff her foot.
It took the little neighbor boy 5 minutes (for the foot-sniffing thing) when
she was outside on lead. Why? Because he was busy playing - ignoring her. She
was interested in his ball and not threatened in any way. As soon as he tried
to pet her, though, that was it. She moved off. Had he remained still, she
might have gotten even closer.

Don't give up on your girl. She doesn't understand what's happened. She's
only doing what she feels she must. So, it's up to you to find out why she
feels she must, then go about winning her over HER way. Like humans, cats are
unique beings. It may take weeks for her to trust you enough to sniff you now
- be patient.

I hope everything works out for all of you.