Friendly sibling cats dislike each other after move

This is a strange cat behavior problem and I don’t have a ready made answer. Or any solid answer except some guesses or more questions. The problem has been raised by one of the Catster visitors and we are going to try and find a solution because the Catster site can’t πŸ˜‰

The Problem

The cats are litter mates, siblings. They were always best friends and got on very well, grooming each other and so on. Their owners moved home. They had to fly to their new address which is in a different part of America. The cats were shipped by air to the new address. I am not sure if they were in the hold of the aircraft or in the cabin. I have presumed they were in the hold. After getting into their new home the siblings decided that they disliked, even hated each other. After several weeks they became more friendly but fell out of friendship. When one approaches the other he gets hissed at and swatted.

That is the scenario. What is the solution? What has happened?

Cat at airport
Cat at airport. Photo by The Consumerist.
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The Solution

We can’t find a solution until we know what has caused the change in behavior. In my experience when siblings fall out in such a way it is usually because of a change in their scent. They can no longer recognize each other. I will pursue that argument initially.


Cats, including siblings, recognize each other by their smell. I guess sight is also a factor but if a cat’s scent is removed, cats that at one time were friendly will no longer see this cat as a friend. The cat with no scent, or a different scent, becomes a complete stranger. It is as if a stray cat walked in off the street instead of a well loved sibling being in the room.

Because the sibling becomes a stranger he gets hissed at because he is intruding on the other siblings’ territory. If the scent of all the siblings is removed or changed the siblings are no longer siblings but strangers to each other. They have to adapt to get on. This is what appears to have happened. Initial hostility has given way to reluctant tolerance with the odd flare up. There is, at best, an uneasy peace.

I have to conclude that the scent given off by these siblings has not returned to the way it was when they lived together at their previous home.

If that is correct, and it might not be, what could cause a cat’s scent to change for a long time or permanently?

One possibility is the conditions under which they were shipped. The crates or environment in the aircraft may have given off a chemical that has been impregnated in the cats’ fur. It may have been ingested and is coming out of their skin.

Alternatively, they may have been vaccinated etc. and the vaccine has changed their scent. I have not heard of this happening but it seems to me to be a possibility albeit a very long shot indeed.

There may be something in the air in the new home that is masking the cats’ scent, which has confused the cats.

I presume that the cats’ owner is not bathing the cats regularly. If she is that would remove scent and cause the problem.

Travelling Conditions

It may be the case that the cats went through a traumatic journey in the airplane when shipped to their new home. Alternatively, they may have suffered some sort of traumatic event at either of the airports. This may have left them in a state of defensive aggression towards anything and everything including each other. If they were in the hold of the aircraft one of them may have become upset and caused a breakdown in the group friendship.

What To Do

Reestablish their natural scents or try and find out if anything happened before, during and after the flight that may have impacted on their body scent and/or psyche. Then pursue a course of treatment that corrects the changes.

16 thoughts on “Friendly sibling cats dislike each other after move”

  1. We just moved into a house 6 houses down from my mother, she is moving in with us. We used the same cat carrier that they have always used and just walked one at a time down the street. We used one of their blankets inside of it so they would have a familiar smell. We have 3 siblings and one that isn’t related but is very close to the runt of the siblings, the 2 larger siblings were very close and now the sister hisses and swats at the brother. I can’t see how his smell changed in a 2 minute walk down the street, the only thing I can think of is that the carpet being shampooed before we moved in and having all different furniture from what my mom had we used my moms coffee table and computer desk but that’s it.

    • The reason might be as you describe. Another factor might be the move to a new home. Remember that moving home is stressful for domestic cats because they have moved from their settled territory and routines. It takes time to reset territorial rights etc.. Give things time to rejig and throw in plenty of playtime. When you play with a cat using a tease they forget the stresses and loosen up. The stress may have triggered her temporary animosity towards the brother. It might be her establishing her territory over the brother. She may be more forceful than him in this regard.

  2. I came here to see if I could find some help as I moved house yesterday, I done all the normal things like give my two 10 month old brother and sister kitty’s their own blankets etc for the hour and a half car journey, however I stupidly put my male kitten into my neighbours borrowed cat carrier, although both my kittens were partly sedated with a natural calmer my female has become aggressive towards her brother, after watching and studying them overnight I truly feel that the scent from the neighbours cat carrier has had a huge impact due to it most likely having scents from his home and his own cats, my male cat wanders and curiously does plenty wandering bad scent marking and sniffing in my new bedroom but little miss is hiding right under the duvet and didn’t eat or drink or even pee for well over 12 hours which is actually a short amount of time, I have brought in their own toys, my unwashed duvet set and clothing I have worn and that has definitely worked to encourage her to come out from hiding but she is still growling and swiping at her brother to his dismay poor boy doesn’t understand what’s going on and neither does she, saying that I do believe that once they settle in to their new room (I have confined them to one room) and adjust to all the new sights sounds and smells I am confident all will be ok, if not then a simple Rei troduction will be necessary but for the time being I am leaving them alone to readjust to one another and only playing if they actually want to and are confident enough to do so, in these instances I believe that patience is key and you must allow your cats to adjust to their new surroundings, I have a plug in diffuser which helps a lot and I also have nutracalm capsules for them in severe cases and these definitely do work a treat but only on the advise if your vet.
    I hope this may help someone else or if anyone has any suggestions to help I would appreciate the feedback.

    • Hello Janice and thank you for a great comment. Although I’m sorry to hear about the difficulties that you are experiencing.

      I agree with your diagnosis. The brother has picked up the scent of a strange cat and his sister no longer recognises her brother.

      I think what I would do is to give him a bath to wash off the scent. I wouldn’t rely on time and his own cleaning to do it. Or give him a wet wash with a damp cloth. That will leave a different scent on him which also may put his sister off but it will fade quickly. In my experience once the scent of the strange cat is gone the sister will relate to her brother as before immediately. However, I can give no guarantees that this will work. That said I had a very similar experience with a brother and sister cat couple that I looked after years ago. The sister fell into a pot of paint and I had to wash her in a sink. This changed her scent and her brother rejected her until she dried off and quite quickly within about five hours things went back to normal.

      Could you keep us updated on this? In the meantime I have decided that this makes a good article so I will publish your comment as an article together with my comment. Thanks again.

      • Hi there, I’m so sorry for such a late response, I washed my boy cat down with a damp cloth and a tiny little bit of baby dove bath wash, I then dried him with a towel and removed the other cats carrier he was travelling in from the room, it took a couple of days but with a little help from a felliway plug in and calming tablets for cats, all was well, they went back to being very friendly after my female went to investigate her brother while he was snuggled asleep on my bed, she gave him a good sniff and then just simply lay down next to him and started to clean and lick his ears and neck then fell asleep snuggled together so that was her back to normal, the only problem I have now is that when they are out and about in the fields around the house, usually when he returns or she does and they go to sniff each other she hisses at him and “slaps” his head but this is only happening when their is a different scent like when she’s in heat even tho she has been neutered there still is some sort of scent that shows she’s at that time somehow, even the bijon frise dog tries it on with her every few monthsπŸ™„πŸ€£. Anyway as I said all is good now and they are both very settled, very loved and very spoiled and r living back in harmony thankfully. Time and patience is key (I also rubbed his face slot to get his own scent on my hands then I would pet the female so she picked up his own scent again) this also worked wonders for me.

  3. The usual first thing to try in these kinds of situations is to ‘reintroduce’ the cats the same way you would if they had never met. Put each in different rooms, trade scent, the usual drill.

    When you move you should get the cats into a quiet part of the new house and let them adjust to it slowly as well.

  4. I believe its a combination. My cats have been known to slap at each other when one has just come from the vet. Something about that clinic smell the other cats don’t like. We’ve even considered bathing both cats back when we only had a few.

    Of course the trip itself was stressful. But think about being in a new home. That has to be traumatic to have to learn your way around a new place with lots of new smells. Did the previous home owner have any pets the cats may smell?

    We recently had to bring home sisters adopted out over a year ago. Sheela, who’s a Maine Coon mix was shaking from head to toe. Both girls refused to eat the first 3 days and had to be syringe fed KMR milk.

    Just don’t let them hurt each other and give them time to adjust. Perhaps get some waterless shampoo and rub a bit on each of them to get them smelling more alike. It takes our cats an average of 3 weeks to adjust to new surroundings.

  5. “SCENT” plays a very important role in cat recognition amongst themselves. If two cats have always been living together then remove the scent of one cat or spray it with perfume or give it a shampoo bathe and then you will find a total different behaviour from its sibling or its living mate.I am talking from personal experience between my two traditional Persian cats who would quarrel to death without my intervention after being given a bathe.I have experienced this behaviour on at least 3 or 4 occasions and now have totally stopped giving them a “Shampoo bathe”.It would take almost 2 days for the two cats to become friends again, myself always on the alert with a stick in hand to separate them if they got into cat-fights.Matata, the tom cat is the kitten of the queen cat matahari having been associated with her from birth, yet, after a bathe they were total different cats and tomcat matata would always attack his dam matahari and not vice-versa.Male cats are more territory dominant and hence aggressive.I strongly feel that “SCENT” difference due to change of location and address could have led to the cat-fights amongst these sibling cats that were once friendly.

    • Thanks for the sharing your experience, Rudolph. I think it is a combination problem: scent change and traumatic events (moving home and shipping fright). I would hope that they will gradually settle down.

  6. Gosh that is awful and must have been unbelievably traumatic – especially if they were not used to travelling at all, in a car or any way. I wonder how long ago it happened? Do we know? I think it might be some kind of serious shock from the events that has left them both extremely uneasy. Perhaps they are scared still. Sounds like it. I’m sure smells come into it to what with them being in a new home but I’d say first and foremost its a massive amount of fear from having had the most shocking experience of their lives ever. The hold would freak anyone out – can you imagine the noise? Insane!

    I think they need alot of time to get over it and get back to normal. I mean literally a couple of months – they need to pretty much forget it. If that much time has already passed then I don’t know. One thing though – is it one of the cats hissing at the other or is it mutual. Does the issue seem clearly one sided in any way?

    What will help are all the usual things. They of course must not trust their caretakers much after that ordeal so they need to be looked after loved and played with whenever and wherever possible. To be honest – if they went in the hold ‘if’ – sounds possible – then I would say that was fairly negligent of the caretaker who perhaps didn’t know better. The cats need to feel like this wont happen again – ever. They need alot of love. They are also in an entirely different place with different sights and smells. They have really a lot to deal with and it is compounded by the fact of what they went through to get there. If they never went on a car journey before this then it would have made it all the more intense.

    Take good care of them and see if they want to play – if they don’t – give them time, and they will. Time might well heal this one. I hope they can go back to at least having each other and loving each other as before according to the original statement.

    • Nice comment. I think you are right, Marc. I think a major contributor is what happened during “shipping”. I think it was a traumatic event for them and it has shaken them up. They may have turned against each other during shipping on the basis that they were in the hold of the aircraft.


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