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ADDING NEW CATS TO EXISTING CATS. by Celia Haddon, www.celiahaddon.com


Your responsibility should be primarily for the cat or cats already in your care. Think hard before asking an very elderly cat to put up with a new companion. Kittens may be accepted better than an adult cat, but kittens often pounce on and pester old cats. Some old cats will mother a kitten; others (like my eight year old) definitely won’t! A very energetic kitten can make an old cat’s life a misery.

It can take months and months for harmony and sometimes the cats will never be friends. An introduction takes at least a month – don’t hurry it. The slower you do it, the more likely it will work out OK. Cats which are used to a multi-cat household will be less upset than a cat which has lived alone. Get a kitten from a cat shelter, which will promise to take it back if the introduction really doesn’t work out. A male female mix is probably better than all female.

Be careful about accepting the local stray into your home. Ask yourself if an existing cat should have to put up with a former stray, who may bully her/him. Also think about checking for FIV, the cats Aids equivalent, before final acceptance.  In the case of a stray cat, you can feed it, then when it is tame enough find it a new home via the Cats Protection League or the Blue Cross.


The best way to introduce a new cat is to give it an indoor pen with food, litter etc. If you can’t borrow or buy one, give the new cat its own room, so that it feels it has safe territory. Shut doors windows, and block chimneys before letting it out. If possible a retreat hole like a covered cardboard box with entrance hole, or a cage-den . Put familiar toys (if available), feeding bowls etc. in the room. Put litter tray in the room. You can’t expect a cat to go outside in the first few days, and if you let it, you may not see it again.

Mix the smells. From the point of view of a cat, anything which smells strange is an intruder. Give the new cat something to sleep on which smells of the old cat, then visa versa. Using same grooming tools on both cats. Pet one, then go to next room and pet the other. Transfer used litter from the new cat tray to the old cat’s tray and visa versa to mix smells.

If you have a large indoor pen, all this can be done while the kitten spends time in the pen. You can start feeding them in the same room – one in the pen, one out of it and the other side of the room. If you have the new cat in a separate room, feed near the door so that the cats associate each other with food. Also tie a cat toy at both ends of a piece of string, and place under the door. The idea is that they play with the toy from either side, associating each other with the pleasure of play.

Vets can sell Feliway. It reduces anxiety and will therefore help. Spray it at chin height on things a cat would rub with its chin, all round the new pen and the room where the pen is. Or get the easier plug-in Feliway Diffuser which lasts for a month and will reduce feline anxiety in the room in which it is used.

If you don’t have a pen, first transfer all the smells while the new cat in the separate room. Then use a cat box with the new kitten in it for the first introduction. That way, they have the chance to see each other in safety. Watch the body language closely. Introduce the animals together when the new cat is used to his room and territory. Make sure there are escape routes for whichever cat wants to run away. Do not leave strange animals together alone. You must be there to make sure accidents don’t happen.

Staring, puffing up fur, hissing, growing etc may happen. This is OK as long as it isn’t translated into aggressive action. Do not intervene unless you think one cat is being seriously hurt. Do not pet the newcomer in front of the old cat to begin with. Give the old cat extra affection.

It’s very important that there are enough feeding bowls, water bowls, litter trays and beds to go round – so that the cats don’t have to compete for them. Install water and food upstairs on a tray as well as downstairs in the kitchen. Litter trays in more than one location. One litter tray per cat and one over is best.

Accept that they may never be friends. If they tolerate each other, that should be good enough. Try to make sure they both have safe places to retreat to. But if one cat is seriously bullied — not able to eat without being hassled, ambushed on its way in and out of the litter tray, harassed in its cat bed, spending all its time under the bed, then think of rehoming.

Spraying – if this starts you MUST get Feliway as soon as possible. Ask for my spraying leaflet.


The CPL has a free leaflet called Living in Harmony, send a large s.a.e. and a few extra stamps to Cats Protection League, 17 Kings Rd, Horsham, West Sussex, RH13 5PN.

They also have a leaflet called Moving House With Your Cat, which may be relevant. I have some notes on cat-hating dogs, but, on the whole, a cat should not have to live with a cat-hating dog — the daily stress will be too much for the cat and, of course, it may eventually be killed outright.

Consult Introducing our cat to other cats and dogs on www.fabcats.org or send an s.a.e. and small donation for it to Feline Advisory Bureau, Taeselbury, High St, Tisbury, SP3 6LD.


DISCLAIMER: All normal safety precautions should be taken when dealing with animals. Whilst I make all reasonable efforts to ensure that the advice and information provided on this site is accurate, it does not constitute veterinary or expert behaviour advice. Because it is not based upon an analysis of your own personal circumstances, it may provide information, which is inappropriate for you and your animal. In addition the information and practice upon which it may be based may very well be subject to advance and change and despite my efforts the information  may not always be up to date. For this reason the information on this website is no substitute for the advice of your own vet or pet behaviour counsellor based upon a full understanding of you and your animal’s individual circumstances.  Accordingly, you are urged, if you do require advice upon which to place full reliance, to seek the assistance of a vet, a pet behaviour counsellor or some other suitably qualified professional person having the relevant expertise to assist you with your problem. As far as the liability of myself is concerned all implied warranties and conditions are excluded to the maximum extent permitted by law. Neither I, nor my suppliers or affiliates will be liable to you in contract, for negligence or otherwise in tort or otherwise for any indirect, consequential, special or incidental damage or loss arising from your use of this information nor for any information contained in it or omitted from it.

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