Fighting Housecats Gone Wild

Question
Here is my question, I have two cats, one male named Stanley and one female named Sara. Stanley is neutered and Sara is not spayed because she was the runt of her litter and we were worried she was just too small, she has never been pregnant. They are both about six years old. Stanley and Sara weren't too fond of each other before but mostly they got along until recently. Stanley has a habit of trying to get outside whenever the door is opened, he is very curious, one day when we were feeding one of the stray cats(we call him Casper and he is male)around here he got out, Stanley ran into the shed in our backyard where Casper usually sleeps, we rushed to catch him and bring him inside, but before we could Stanley approached Casper, they only sniffed each other before we scooped Stanley up and brought him inside. Sara was watching as we brought Stanley in and we set him down Sara approached him, sniffed him and then started to hiss and then swipe at him. Stanley ran and she ran after him, but because Stanley is much bigger than Sara it quickly became Stanley chasing Sara. She ran behind the couch in our living room and Stanley ran up to it but she would not let him go any further, she was hissing, practically screeching, the noises she was making were indescribable. We think she was trying to scare him off because she thought he was really going to hurt her and we didn't want to find out so we pushed him away but he didn't want to leave so we had to grab him and put him in another room. Sara was still hissing after we put him away, even when we tried to comfort her, so we just left her alone for a little while but that didn't help so we had to put a cover over her so we could pick her up, then we put her in her carrier in another room. After this happened they could not be in the same room together at all unless they were in their carriers. Once Sara got loose when we were swapping them out(we give them an equal amount of time everyday outside of their cage because they can't be together), and she was running around the house and she saw Stanley who wasn't in his cage and she started to hiss and then they went after each other, Stanley chased Sara into a corner and she was so upset that she had an accident and peed on herself and the kitchen floor, we grabbed Stanley with a blanket and put him away, Sara went to hide. It has been almost a month now since they stopped getting along and we have been giving them their turns out, it had appeared that they might have forgotten about their confrontations so we tried to reintroduce them but they hadn't, it seems they have only gotten worse, Sara went over to Stanley and sniffed him and it seemed like she didn't mind him but then Stanley went over to her and she didn't like that, they automatically started to hiss and moan and swat at each other, being veterans by now we swooped in and grabbed Stanley and seperated them.  Now they won't even be alone in their cages if the cages are too close together. We are feeling very helpless about what to do, getting rid of one of them is not an option, they are family. Do you have any answers? Any advice is appreciated. Thank you.

Answer
Hi
yes this is a problem i have come across before. it is a strange issue which seems to be caused by fear caused by something quite small often. In this case your older cat may smell slightly different from being outside, even if it was only for a short time. it may have been caused by the way the family reacted when Stanley got out. cats are very sensitive and if there was shouting or fear from you then the cat could have picked up on this. in any case the current situation is caused by fear.

The only way the two cats will be able to get over this is to be introduced to each other in small sessions in a safe environment. it is also important that you are very relaxed about it all too, other wise they will pick up on your anxiety. if they hiss, they hiss, don't worry this is a normal reaction and simply means i am afraid leave me alone.

the way to introduce them is to have one in a carrier with the other outside. this way there is no fear of actual harm. The process has to be carried out over a period of a week i'm afraid as the cats have to learn to trust each other again.

I have described the process fuller here

/introducing-cats.html

Don't worry i'm sure things will eventually settle down. the cats will calm down again as long as everyone remains calm around them.

best wishes Kate