I have a fairly long document that I put together to explain how I
introduced Duffy and Holy.  I did this at the request of some other people
who wanted the information, and I did not want to continually post it to
newsgroups because I had previously posted the information (some in bits and
pieces) several times.  I will be happy to send it to you by email after I
get home from work this evening if you would like to see it.  Let me know if
you want to see it.  In the meantime, please let me emphasize the point that
you should plan to do this in very slow and gradual stages.  You will
probably set things back considerably if you try to force an introduction.
This means that you are actually fortunate that you had to leave the cats in
separate rooms when you went to work today.  You can see a "history" of what
I did if you look at the two links under my signature.

MaryL
(take out the litter to reply)

Photos of Duffy and Holly:      >'o'<
http://tinyurl.com/8y54 (Introducing Duffy to Holly)
http://tinyurl.com/8y56 (Duffy and Holly "settle in")

Congrats on getting this far! Nervous cats can take a lot of patience.
My Isis hid in the bathroom for two weeks.

I would recommend taking a couple days to get the cats used to each
other's scent. Get a towel. Rub it on Marigold. Then take it in the
other room and rub it on Whiskers. Do this several times a day and they
will start to smell more like each other, as cats who live together do.

Then you may want to shut Whiskers in the bathroom or a bedroom for a
short while and let Marigold explore the house without having to see
Whiskers. They will smell each other this way, since Whisker's scent is
in the home and Marigold's scent will be throughout the home after she
explores it.

After a week or so, I'd try an introduction. While Marigold is
exploring, let Whiskers out of the bedroom or bathroom. They meet each
other, but don't associate you specifically with the meeting. I would
not recommend direct contact if either cat is aggressive, but it sounds
like Marigold is not the confrontational type and Whiskers may hiss, but
if she didn't stalk Marigold and have a fit, she probably isn't overly
confrontational either.
Let Marigold run into the other room if she wants to. Don't force
anything. If the cats don't fight, leave the room open for awhile to see
if Marigold comes back out. Do let her have some security by closing the
door again if she seems overly scared.

If she gets scared, she may not want to come out again for awhile. Don't
force her. Just give her the opportunity to explore while Whiskers isn't
around (as before) and build up her confidence. Then try again.

Let us know how it goes.

--
~kaeli~
Any sufficiently advanced technology is indistinguishable
from magic.
http://www.ipwebdesign.net/wildAtHeart
http://www.ipwebdesign.net/kaelisSpace

Fisrt, you have to realise that an old cat is not going to have its
territory invaded without objection.  And a two year old cat is adult, not
subject to kitten safeguards that most cats show.  So you will get fights.

If you can be there to referee the battles it might help.  Else let them
work it out by putting them together. But that is not what I would do unless
you have to due to work comttiments, etc.

Its been nearly a month since we adopted two neutered male cats-one
senior (12 yo) and one adult (3 yo); so here's my advice FWIW. The
younger cat is large (12 lb); the senior cat is a jumbo (about 18
lbs). Our situation is a little different since we were not adding a
cat to a household that already had one, but some aspects of our
experience may be helptful.

At the advice of the vet, we kept them  both isolated in seperate
rooms to get them as comfortable as possible with their surroundings,
then started introducing towels which we had rubbed one cat with into
the other cat's room after a couple of days. Then we swapped rooms.
After about four days, we started taking turns letting each cat out to
explore the rest of the house while the other was in their room.
Finally, after a little over a week, we let them out in the house
together under supervision and alternated letting one have the run of
the house overnight while the other stayed in his room.  After a few
days of doing this, we got to a point of just setting them up in the
house together 24 hours.  Our approach in introducing the cats would
probably need to be modified in a situation like yours.  I don't see
the need or desirability for restricting the resident cat to one room
except maybe for short periods of time while the new cat is allowed to
explore.

We had a few bumps in the road but nothing compared to what some
people experience.  Basically, after they were both allowed to have
the run of the house the older cat was pretty dominant and would
occasionally go after the younger one.  We don't know the background
of the younger one, so we don't know if he was an only cat in his
first home.  It settled down to occasional spats where the younger cat
would cower a bit, which seemed to encourage the other a bit.  The
dissapointing thing was that the younger cat was, to some extent,
stressed by the situation and you could see him looking over his
shoulder for the older one, who seemed to resent attention being paid
to the younger one. The two tolerated each other most of the time with
spats once every day or so. The younger cat had been very sweet and
loving at the shelter but that part of his personality only showed up
for short periods when he was away from the other cat.

The vet indicated that this was a dominance issue that would probably
work out in time but at her suggestion we tried Feliway-two plug-ins
as well as the spray. This made a fairly dramatic difference.  The
younger cat seemed to become *much* more comfortable and stopped being
cowed by the older cat.  The younger cat has become much more
affectionate, more like he was at the shelter.  This seemed to confuse
the older cat a bit at first-I caught him acting like he was going to
spray a laptop bag in the first few hours after we started the Feliway
(he had never acted like he was going to spray at all before);
however, he seems to have adjusted to the change in "inter-cat"
dynamics and things seem to be rolling along very well now.

It seems from what I've read that using Feliway to calm cats down or
help smooth out dominance issues is kind of a crapshoot-some people
report it working like it did in our case and some people try it with
little or no positive effect.  It *is* fairly expensive, and in our
case the vet  charges the list price for it.  You can find it much
cheaper on the web if you can afford to wait a few days (next time we
get it that's what we will do).

Maybe some of the above will be of help to you.  I would say we
learned to be patient and above all not rush things or get unduly
upset if the cats don't become best buddies immediately.  I think this
is often a "three steps forward, one step back" type of process.  I
believe that the results are going to vary to an extent from case to
case based upon the personalities and backgrounds of the cats
involved, so what works in one situation is not guaranteed to work in
another.

Anyway, best of luck.