A few things that helped my two get used to each other:
1. Feliway plugs ins and spray for areas that caused problems.
2. Composure liquid max 2x a day mixed in wet food. This was given to the more aggressive cat. I noticed a huge difference. It took a few days, but it really helped the more aggressive cat to feel less agitated.
3. I used a cheap wooden screen door from Lowes that I attached to the door frame with cheap tension rods. The entire set up was less than $30. I also didn't have to deface the door. I had tried stacking baby gates, but never felt they were secure enough. The screen door allowed the new cat to hear, see and smell the house while still being safe in his room. I did put a baby gate in the door way as extra protection. I also only did this when I was home to supervise. The screen was cheap and it could have been knocked over if a cat worked on it for awhile. Once the cats would eat on either side of a closed door I moved to having them eat with the screen door up. I had to start about 3 feet from the door and gradually move it until the were just a foot or so apart. If there was hissing I had moved too quickly.
4. Another thing I used was a large dog cage. I covered it on 3 sides with a sheet. This allowed the cats to smell and see each other, but safely. I used plain cooked chicken as a reward and as a way for them to associate good things with one another. I did this 2-3 or more times each day. I only had one cat that would go in the cage, but he didn't mind.
5. Play with the cats individually. Play until they are really tired. Get a da Bird toy and wear them out. Tired cats are much better behaved! Also I was told not to used catnip during this phase. It can cause aggression.
6. I rotated who was out and about and who was put away. I always gave the new guy some time out of his room. Yet each night the new cat was in his safe room.
My two took exactly one year to get acclimated to each other. The new cat I brought in was a feral/stray who was used to fighting for his territory. I worked so hard to get them used to each other. Now they hang out together, sleep together and play. I never would have thought it possible.
Take it slowly and push the challenge line from time to time. If you need to go back thats ok.
Here is a picture of my screen door set up.
1. Feliway plugs ins and spray for areas that caused problems.
2. Composure liquid max 2x a day mixed in wet food. This was given to the more aggressive cat. I noticed a huge difference. It took a few days, but it really helped the more aggressive cat to feel less agitated.
3. I used a cheap wooden screen door from Lowes that I attached to the door frame with cheap tension rods. The entire set up was less than $30. I also didn't have to deface the door. I had tried stacking baby gates, but never felt they were secure enough. The screen door allowed the new cat to hear, see and smell the house while still being safe in his room. I did put a baby gate in the door way as extra protection. I also only did this when I was home to supervise. The screen was cheap and it could have been knocked over if a cat worked on it for awhile. Once the cats would eat on either side of a closed door I moved to having them eat with the screen door up. I had to start about 3 feet from the door and gradually move it until the were just a foot or so apart. If there was hissing I had moved too quickly.
4. Another thing I used was a large dog cage. I covered it on 3 sides with a sheet. This allowed the cats to smell and see each other, but safely. I used plain cooked chicken as a reward and as a way for them to associate good things with one another. I did this 2-3 or more times each day. I only had one cat that would go in the cage, but he didn't mind.
5. Play with the cats individually. Play until they are really tired. Get a da Bird toy and wear them out. Tired cats are much better behaved! Also I was told not to used catnip during this phase. It can cause aggression.
6. I rotated who was out and about and who was put away. I always gave the new guy some time out of his room. Yet each night the new cat was in his safe room.
My two took exactly one year to get acclimated to each other. The new cat I brought in was a feral/stray who was used to fighting for his territory. I worked so hard to get them used to each other. Now they hang out together, sleep together and play. I never would have thought it possible.
Take it slowly and push the challenge line from time to time. If you need to go back thats ok.
Here is a picture of my screen door set up.