Been introducing for 7+ weeks now. We have so far made slow but steady progress. The two cats eat side by side, and can sleep and play in the same room, although the cat reacts negatively to the kitten approaching her. They haven't slept or played together even once, and both exhibit litter box aggression.

The cat sometimes swats at the kitten when in proximity, and the kitten sometimes runs at the cat and tries to wrestle. We are sure that he is trying to play, but then the female cat will hiss and growl straight away, and we separate them so it doesn't become a fight. Often she hisses and growls when they'we been close for a few minutes.

Progress seems to have halted. Could that be because the kitten is not neutered yet? He is 4,5 months old. He started crying by the front door a lot last week, although he doesn't spray or anything. Can it be that he is entering puberty, and our cat reacts to the hormones? - he will be neutered in 3 days.

And what else can we do? We play for hours a day with them, both in separate rooms and in the same room, reward with treats for good behaviour, feed them together 3x a day. They are only together when we can monitor them, and we try to avoid any and all bad experiences. They live in a large, very catified apartment with lots of resources.

We are at our wit's end. Any advice is appreciated.

  • Thank you for the replies! Aug 13, 2023 at 11:32

2 Answers 2


Addressing the main question: Further progress may simply take time. They're tolerating each other; that's a good start. They'll figure the rest out.

In human terms, the 14mo female is a teenager, and the 5mo male is the annoying subteen kid brother. Even if you basically like the brat, he's often intrusive and demanding...

("Go play elsewhere, kid. I'm not in the mood for silliness right now.")


Neutering the male might indeed make a difference, females sometimes react aggressive towards intact males in their territory if they are not in heat.

However, if eating side-by-side is working and even sleeping in one room is not an issue, things are generally going well and they might just need more time.

Keep in mind the age difference is significant at this point and so are the energy levels, 1+ year old and 4 months old is huge and a completely different story compared to if they were 1 year and 2+ years old respectively.

As for the litter box aggression, it might be worth investing in an additional litter box or two.

While many behavioral experts and book authors on the subject go with a rule of thumb of one box per cat plus one extra, this doesn't necessarily have to work for the specific personalities of your cats.

In our case for example, we've found that two per cat plus one extra seems to be perfect, assuming these are regular litter boxes that might be on the smaller side of what you can buy (we actually use two huge under-the-bed containers filled with litter as the main restroom, and have three small ones as auxiliary, which in total size comes down to around 7 normal boxes you'd buy retail, for 3 cats).

It also allows you to spread the boxes in the house more if needed, and having litter boxes on opposite ends of the house makes it impossible for one cat to guard the boxes when it is in the mood for restroom pranks.

Also worth considering that not all litter boxes are equal as far as your cats are concerned, many have preferences and it might be that if you have all different models, only one is "the good box".

It might help looking for clues here, e.g. if one specific box is preferred and fought over and in that case buy the same model again to replace another one they don't fight over.

  • Accepted by who? I know I've heard that said, but I've found that N+1 boxes often works fine if there are N cats being obnoxious about it, for N being a low number. Possibly plus one box per additional floor, if one or more of the cats is elderly and may not be able to navigate stairs as easily as in the past.
    – keshlam
    Aug 9, 2023 at 5:42
  • 1
    @keshlam I've clarified a bit, I think I was trying to say basically the same thing, it really depends on the personalities of the animals, and what various experts say on the topic should be considered more of a guideline than gospel.
    – bgse
    Aug 9, 2023 at 14:57

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