馃悎introducing a new cat without starting a war

did this twice now (3 cats total). every step here exists because I skipped it the first time and paid for it

01
keep the new cat in one separate room for at least 3-4 days, full stop
she said no the first time I tried a faster timeline and I believed her
02
feed both cats on either side of the closed door, bowls a little closer each meal
food = good things happening near the scary smell
03
scent swap before any visual contact: rub a sock on one cat's cheeks, leave it near the other
swap their bedding too if you can stand the smell for a few days
04
let the resident cats sniff a blanket from the new cat's room, don't force noses onto it
05
do the same in reverse: something from the resident cats' space goes into the new cat's room
06
crack the door for supervised sniffing only once everyone's calm around the scent swaps, not before
this is the step people rush and it undoes the whole scent-swap phase
07
first face-to-face is short, behind a baby gate or door cracked with a doorstop, food on both sides
08
watch body language, not just hissing
a hard stare and a slow-swishing tail is worse than a hiss, hissing just means "back off" (vet approved read, not just my opinion)
09
end every session before anyone gets tense, even if it's going fine
10
increase time together gradually over 1-3 weeks, don't jump to full access on a good day
one good afternoon isn't proof, three good days in a row is
11
keep separate litter boxes and a spare, even after everyone's fine
12
if there's a full-on fight, go back to the last step that worked and slow down again
we regressed to scent-swap only for a week after cat #3 hissed for two straight days. worth it

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