WWCOJD - Advice by those of you that ...serve cats (aka cat owners)

And yes...new cat would be from an animal rescue...

It all depends on the personality of the cats, I think. In my (limited?) experience, things will work out most of the time.

My next door neighbour (we share a wall) has 3 cats. She got each one, one at a time from the animal shelter. I don't think that she considered age or sex, first was male, second was female (older I think, but close to the same age), third was male (younger I think, but also close in age) and they get along all right.

I take care of her cats when out of town, and sometimes let them into to my place with my very friendly slightly younger (7 y/o) male cat and they get along great. No problems right off the bat. Same thing if I take him to their place.

I used to volunteer at the SPCA and we'd let cats out together occasionally (provided we knew their medical history) and they always got along fine.

My parents have 2 siamese cats that were littermates and they only get along with other siamese cats. Snobs, I guess. But I'm sure they could be socialized if necessary.

So in my experience, things works out more often than not. I'm sure that the volunteer/representative from the humane society could help you assess the other cat's personality.

My female (Copy)  has shared the house with a multitude of cats over the years.  Copy was the little one with Cleo but Cleo was extremely timid and never interacted with anyone (person or cat).  Eventually Cleo died and we got Mr Worf.  Copy tolerated him then they got to be buddies.  Unfortunately Worf threw a saddle embolus and died suddenly.  We got Oscar and Mocha about a week apart from the vet.  Still have Copy.  She wasn't too happy when the boys arrived but does like them now. 

We left the boys isolated in bathrooms with short supervised times out with Copy until they got along better.  Oscar was in the house about a week before Mocha because Mocha was sickly and I couldn't effectively isolate him until Copy and Oscar were okay. 

Both Copy and Oscar claim me as their person.  If Copy is on my lap Oscar will sit nearby until Copy gets sick of him being near me and goes away.  He will immediately take my lap.

Oscar was bottle raised at the vet and has a lot of issues (see cat declining thread about a week ago, he's the one who pees on the floor and poops right in front of the box no matter what the litter).   

Mocha was found under a dumpster, had goopy eyes, fleas, mites and worms....I took him home from the vet when he was a little less sickly.  The girl that found him works at the vets office and every time I take any of the cats in she asks about him.

I have an older cat and we decided to bring in another kitten.  I wouldn't say they don't get along, but it has been interesting to watch.  Shadow (the older cat) is not so into playing or anything.  Cougar however is all about playing.  He'll run up to Shadow and chase her all over the house or just sit there and bat at the tail.  Shadow sits there and hisses and they do get the paws up at each other.  For the most part though it is all just fluff, nothing really comes of it and more often then not they co-exist just fine (cause Cougar can sometimes focus on the dogs and leave Shadow alone). 

My mother however brought a kitten in with her already established cat and it seemed like it really stressed that cat and it did end up dying shortly there after.  My mom felt all kinds of guilt over that.  I think that is rare though.

If you want another cat though make sure your getting that cat for you and not for your other cat.  They may co-exist just fine but they may never be "friends".  And now your dividing your time between two cats. 

I think in general things work out.  I introduced a female kitten (lexi)  to my very spoiled 10 year old male (KC) and he never really took to her but they co-existed.  When KC died I introduced a male kitten (Charlie) to Lexi who was then 5.  They got a long better but had VERY different personalities.  I recently lost Lexi and introduced a male kitten (Tucker) to Charlie which is going pretty well althoug Charlie is quite jealous of the kitten.  Each has been a very diferent experince and each cat has had very diffferent personalities.