If you isolate the new cat in a closed off room that has a vent from
the forced air HVAC system and a return path, the scents of all the
cats will meld together without unnecessary stress scents being mixed
in.  The new cat will probably appreciate not having to learn about a
large area at once - after release (and after recovering from the
stress of being rehomed), the newcomer will have a known refuge
available while it inspects ever increasing areas of the house.  Also,
when released, the new cat will have a familiar scent, and will know
the scents of the other cats and of the house.  Scent is extremely
important to cats, and I recommend leaving the HVAC fan on
continuously.  If there is no forced air HVAC system to help mix and
distribute the scents, I'm not so sure that the isolation approach has
as much value as it does for me.

--
T.E.D. (tdavis@gearbox.maem.umr.edu)

In my family, we've always just plonked the new cat in among the old
ones and let them work it out among themselves. It's never taken long
before the new cat was accepted, but then the new cat has always been a
young one. I don't know how well this would work with an older cat.
Also, I'd say that if you want to take a kitten, take two, so they can
play with each other, as Lindy might not want to play as much as a
kitten would. My E0.02. :o)

I've introduced adult cats to each other three times. The first time was
when I was looking after Fuzzbox, who used to be my cat, and then was my
mothers. He came to stay with us a few months after we adopted Izzi and
Fenda. We were living in a small flat, and there was nowhere to isolate him,
so I just let him out in the living room straight away. He knew me already
of  course, and instantly acted as if he was the resident cat, and the girls
were interesting visitors. They were all roughly the same age (he was three,
the girls were two) and they got on just fine almost straight away.

Ripley was a stray when he moved in with  us, and as Izzi and Fenda were
indoor / outdoor cats anyway, they already knew him as a neighbourhood cat,
so introductions weren't necessary. Izzi complained about him almost
constantly though, she didn't like him, and never grew to like him. They
rarely fought though, and Ripley was always the perfect gentleman with her.

Introducing three year old Cav to seven year old Ripley was much easier than
expected. We kept Cav in the conservatory for the first day and night, apart
from an hour when he was allowed to explore the living room. That meant that
they could watch each other all night through the glass doors, and also get
the chance to get each other's scent. We allowed them to mix the next day,
supervised, and took Cav back to the conservatory for a 'time out' if they
got too worked up. After three days, we were leaving them alone together.
They did have some spectacular fights and screaming sessions over the next
couple of months, but they get on very well now, and seem to enjoy each
other's company.

Jeanette

Hi, Joy,

I've done it both ways, and a "middle" way, too (keeping cat in
carrier in living room for several hours while the others checked him
out).

I know conventional wisdom is to do it slowly, and that is the way I
have been doing it for several years now.  We have a separate room so
we can isolate the new one, and there are some good reasons for doing
this, including not knowing health status and not yet having
vaccinations done, which I think is safer in that case.  If you
already have taken care of testing and vaccinations, then those are no
longer a reason to isolate, at least.

For me, it has worked well both ways.  With Trill, for instance
(isolated) enough cats had sniffed at the door by the time he was
vaccinate and neutered and all that his introduction was easy.  Mojo
(RB) just got tossed into the soup, so to speak, and every single cat
here adored him in less than an hour.

If you spend enough time with an isolated new kitty, I think it is
okay.  Especially if it is a household with many cats, they may
actually feel safer, and have a chance to get their bearings before
having to deal with a horde of cats ;-)

At any rate, I think a lot of it has to do with individual cats'
personalities, no matter how the introductions are made.  Some will
simply never like others, while others will take to other cats like
they're known each other since birth.

Just my rambling thoughts.  Best of luck!

Ginger-lyn

Joy wrote:

---------------------<snip>----------------------

We've done it both ways.  When we introduced Lady Jane to Misty, who's
long since gone where the good pussycats go, we kept Janie in the
spare bedroom for a week before allowing her the run of the house.
Misty greeted the newcomer in a most un-catlike manner.  She didn't
hiss, spit, or swat, she just ran at Lady Jane full speed and knocked
her 'a.s over teakettle'.

We've had more luck introducing kittens at a more accelerated pace and
Smokey, an adult when we got him,  joined the family rather quickly.
We've only had to take back one cat.  A breeder of Persians let her
queens go for a nominal fee after they'd had a few litters.  They'd
done well by their human, and she wanted to return the favor by
finding them good homes after she was done breeding them.  None of the
standard tricks worked, the newcomer would simply attack whichever of
the cats was closest whenever we tried to let her out of the spare
bedroom.  Poor thing, I hope she went someplace where she's the only
cat.

Regards and Purrs,
O J

You've had lots of answers so I'll just send purrs that everything goes
smoothly.