We have one female cat, seven years old. She has never lived with another cat. When she has seen strays outside she has tried to attack them through the glass door, so I've always assumed she wouldn't be good with another cat.
I had also assumed that my husband wouldn't be good with another cat! However, he has found a young cat (he says in between kitten and cat) at the local shelter that he wants to adopt for our daughter for Christmas. (He's a delivery driver and saw it when he dropped off a package.)
I'm so excited about this idea, but I worry that my cat will be violently opposed to New Cat. We do have a dog, and they get along in the sense that they ignore each other. If he gets in her face she hisses and swats. We also have a dwarf rabbit that now lives in the barn, but lived in the house last winter. When he was out of his cage she was OK with the rabbit as long as he left her alone. He would sometimes try to play with her and she was not a fan of that. She would hiss and swat at him too.
So what are the odds we'd be able to successfully introduce a new cat to our home?
There will be all sorts of hysterics but they generally chill out and at least tolerate each other. It is unusual in my experience for there to be an actual fight, just lots of hissing and showmanship. Make sure the new kitty has a safe place to retreat to that is all her own for a while.
My cat Tita also tried to attack cats through window like yours, and she was pretty nasty to our other cats when we had them, though fortunately she never really injured them.
Twice we had to take Tita to the vet when the dog tried to break up one of the cat fights by jumping in between them. Both times he stepped on Tita's head, and she had to have a large hematoma drained from her ear. After that, her ears were all crumply looking, and she was otherwise okay, but when I moved out to go to college, I took Tita with me, and left the other cat at my mother's house.
After that, everyone was MUCH happier, and I didn't get another cat until Tita passed away.
So based on my personal experiences with Tita, I'd say that all the cat drama and misery would not be worthwhile to me, even if they weren't doing any serious damage to one another.
"In order to really enjoy a dog, one doesn’t merely train him to be semi-human. The point of it is to open oneself to the possibility of becoming part dog."
I just added a puppy to my single cat house hold. Its much harder to contain a puppy than it will be a cat !!
My cat did the same thing. He's very unfriendly to other creatures so we were a bit tenative on adding another 4 legged friend. Our cat is very personable and has a great quirky personality ( seriously our cat plays fetch..for hours!!). We hated for him to change and were very careful at monitoring how he was adjusting.
We have only had the puppy for 2 days and the cat is already curious. Yes, he hisses and the puppy has gotted swatted a few times but he still interacts with us and seems to be adjusting fine. He's also getting close to the puppy on his own terms and time.
I feel we put off getting a puppy for the sake of the cat and everything seems to be working out better than we thought.
Its an adjustment that takes time but these things work themselves out. We are careful about still giving kitty time, puppy time and all together time too.
I have introduced two kittens to my oldest cat, who had been a single cat until about 12. I did both the same way and it worked really well.
I gave one room to the kitten that was his, and his alone. They could smell each other under the doorway, but that was it. I left them like this for a day or two. They hissed and fussed under the door sometimes, but it generally went away. Then I cracked the door open, and let them at least touch noses, but no paws could fit through for swatting In about a week I had the door open, and the little one could explore out when I was there, but when he got scared and ran back into 'his room', older cat was not allowed to follow. This gave the kitten confidence so he didn't feel like he needed to defend himself, and the older cat eventually went 'ho hum, I have better things to do'.
I hear hissing and general 'fussing' about twice a year when they get a wild hair up their a$s. That's it!
My favorite way is putting the newcomer in a large wire crate (with food, toys, box, bed etc) and cover it with a sheet. They can smell and hear each other but not see each other, which calms everything down a lot.
Every day take the kitten out to play while the resident cat is locked away in another room, let the kitten get her paw scent everywhere, and also take in the old cat's scent.
After a week or so, slide the sheet up a tiny bit, or expose a corner, so they can get a glimpse of each other, see how it goes. Every couple days give them a bit more to see until the sheet is completely off. If there are no real fireworks when they interact through the cage, then start letting the little one out for supervised interaction. Usually there's some hissing and death glare looks, but you should be fine.
Introducing little kittens to adult cats I generally find goes easier than adding a new adult. Kittens are pretty oblivious, and so they don't care about the "I hate you, go away!" signals, they just want to eat and play. Just make sure that if it's an older kitten she doesn't bug the older cat mercilessly, there may be some time outs needed