Why do cats smell each others buttholes

I know it's quite weird, but my cats smell each others butts then start fighting, I'm very concerned and I want to know why they do this, they never exactly liked each other, but I just want to know why they attack each other after sniffing each other?

Fighting or playing? Sniffing butts is how animals greet each other. Do the hiss and growl at each other or draw blood?

If they are just kind of rough housing and ankle biting they are playing.

One cat getting close to the other for any purpose can sometimes trigger play. Like if one licks the other, sometimes that could lead to a play fighting session. My young one used to do "lick, lick, bite" -- like a tootsie rolll thing, he couldn't just do grooming. Of if one glomps onto the other as a convenient pillow/for affection, that could lead to play fighting too.

I know it's quite weird, but my cats smell each others butts then start fighting, I'm very concerned and I want to know why they do this, they never exactly liked each other, but I just want to know why they attack each other after sniffing each other?

Fighting or playing? Sniffing butts is how animals greet each other. Do the hiss and growl at each other or draw blood?

If they are just kind of rough housing and ankle biting they are playing.

One cat getting close to the other for any purpose can sometimes trigger play. Like if one licks the other, sometimes that could lead to a play fighting session. My young one used to do "lick, lick, bite" -- like a tootsie rolll thing, he couldn't just do grooming. Of if one glomps onto the other as a convenient pillow/for affection, that could lead to play fighting too.

I think the sniff is a greeting, followed by “and yeah, I still hate you”. Just letting each other know where they stand. If no one is getting seriously hurt, then this is just what their relationship will be.

As far as I know, cats don't usually recognise another cat as friend or foe by sight, which is why there is sudden fighting between two cats, who have always been friendly towards each other, after one comes back from the vet or returns after escaping and smells different from normal. Smell is more important than sight and butt-smelling is a way of determing whether the other cat is friend or foe. If friend - then they may "kiss" (mouth to mouth) or ignore each other, but if foe, then hissing and growling - "get off my back!"

P PhysicalSadness Your cats seem to be a bit unsure about "friend or foe" so they have to smell each other's butt. At least there is still a chance that the emnity will cease - if it was so inherent in their relationship they wouldn't bother sniffing - just attack!

I know it's quite weird, but my cats smell each others butts then start fighting, I'm very concerned and I want to know why they do this, they never exactly liked each other, but I just want to know why they attack each other after sniffing each other?

Any ideas?