Need help integrating young cat and older cat peacefully!

I have had my Devon Rex, Blu for 14 wonderful years. She was my  childhood cat and has only ever been a single cat. Recently, I moved in with a coworker friend of mine and knew he had a very young and playful cat, Penny. I figured the integration would take awhile but would be fairly okay. Penny came from a household with another very young and playful cat that she got along with well. I should also mention that Blu is declawed, and had bad teeth as a young cat that were removed for health reasons. Blu weighs around 6 pounds, and Penny is about twice her size.

Since the move (a month and a half ago), things have gotten worse in terms of integration. At first, my cat would hiss upon seeing her from a distance and would generally avoid being anywhere near her (we kept them separated anyway). I expected hissing from Blu, since she has no social background and so was not terribly concerned. Then, a few weeks later we got a baby gate to install in the hallway so they could see each other but not touch each other. We fed them close to the gate so they would become accustomed. Again, my cat would hiss if she got too close but nothing too serious. When Penny figured out how to jump over the gate and/or squeeze herself through the side, we were forced to take it down and keep the cats in separate rooms.

Since this happened, the introductions have been unproductive to say the least. We open the doors to our bedrooms during small, supervised intervals of the day. Penny, the younger cat, is so excited and playful that Blu's hissing does not seem to matter and she will willingly pounce on top of Blu, swat at her face, and run at her full-speed if she sees her leave my bedroom. Several times, Blu has gotten up to wander around and Penny has chased her down the hallway and cornered her to swat at her. She has not drawn blood, and they don't seem to be full-on fights but it's causing Blu to be extreeWe tried the water spray bottle method with Penny to get her to not be so aggressively playful. This seems to work in the moment but she returns 10-15 mins later to do the same thing. We tried positive reinforcement with treats which doesn't seem to change anything either. Blu has no intention of being playful or friendly with Penny, and is just in self-defense mode at this point.  Penny seems to have very bad playing manners and won't back off of her when she needs to.

Any advice on this situation would be extremely helpful! If they would just coexist and be able to ignore each other, I would be overjoyed so long as they don't fight or terrorize each other.

Thank you so much for any suggestions.

The most important thing to to stop the 'daily supervised visits' immediately. You having them in seperate rooms is ideal and where they should be at this stage, but you have to start again from the VERY beginning.

To do this, read these two articles carefully and then begin again from the beginning, following the steps exactly and slowly until BOTH cats are completely comfortable at each step.  If you rush a step, it is likely and even possible you'll find yourself needing to start back at the beginning again, so really, take your time the first time.

http://www.thecatsite.com/a/the-ultimate-yet-simplified-guide-to-introducing-cats

http://www.thecatsite.com/a/introducing-cats-to-cats

If you have any questions or if anything new comes up as you reintroduce them, let us know- we are here to help!

Finally, please stop using a spray bottle on your cats.  Cats and discipline generally don't mix and can often end up making behaviors worse.  Further, even when effective at stopping a behavior, spray bottles tend to terrorize cats and be an unnecessarily unpleasant and even painful experience for them, and even make them afraid of you. For more info on this, please see this article: 

http://www.thecatsite.com/a/cats-and-discipline-dont-mix

I absolutely agree with tulosai . You have to go right back to basics. That means separate rooms with zero contact, just using scent swapping to start with. When neither cat reacts to the other's scent, you can start on site swapping - again zero contact. Only then can you start the introductions by feeding them on either side of a door/screen door. Go very slowly. Blu is an old lady now, and additionally can't defend herself with claws. She doesn't have the same level of social skills that a cat from a multi cat household would have, and this will make her more bewildered by Penny's actions - its sounds like she just doesn't know how to respond.

You also need to go through the house and make sure that Blue has plenty of escape routes so that Penny will no longer be able to corner her when they do meet again. Make as much use as you can of vertical space to achieve this, and make sure both cats have areas to 'own'.

Other things to consider are Feliway diffusers throughout to help calm frayed nerves, and plenty of active play - particularly for Penny - to drain excess energy in a safe way.

I've been going through a similar situation myself: I have a 13 year old British Shorthair who'd only ever lived with his (littermate) brother (who died a year ago). 7 weeks ago, I took in a stray/semi feral girl who's now about 9-10 months old. For the first 2-3 weeks they had zero contact, and have had very limited contact since then. Asha still hisses at Shadow, and they are both very wary of each other, spending most of their time on separate floors. We're still a long way off acceptance, or letting Asha roam free unsupervised. The first priority all the way along has been ensuring that Shadow, as the existing cat, is comfortable...its been very important that he doesn't feel pushed out in any way.

Good luck with your pair. Please be patient, go really slow, and do your best to ensure that Blu doesn't feel pushed out by Penny's arrival.

Thank you so much for the articles! I'll read them in depth tonight and create a plan of action. Thanks again for all the information and the do-and-don'ts, it will likely make the process much more positive! 

I'm so sorry to hear about your loss That must be tough for the resident cat, and likely  how my cat must feel also. I have been putting a lot of effort in to spend time in my room with Blu to make sure she's not losing any attention or love to the other cat. She seems to be very calm/like herself when Penny is out of sight but immediately stressed when she's near. I think the main thing we have been doing wrong  here is not giving them enough time. I didn't fully realize that it can take upwards of a year for cats to forge friendships so we just need to take our time. Thank you for your suggestions/experience, it helps a lot!

I've wondered about this too, but more in the sense of "new cat and already-here cat", more than "young and old cat". My cats are old, and I'd love to adopt another one, but always afraid one of them (or more) may think they are being replaced. We always seemed to lose one quickly after getting a new one in the past. Sara has a few health issues, but overall they are all pretty healthy and lively. Ok, Maple's lazy - but otherwise good. Even my 16 year old acts like a kitten still at times. 

I'm not wanting to get one for the purpose of having a kitten or anything else. I just love cats so much and would love to provide a home to one that needs one. Since there are so many that do.

Wonderful to see your new comments!! Please keep us updated on how it goes!!!