My cat's last rib feels fat or spread away from his body.

I just noticed that my 14 year old black neutered cat has what feels like his last rib is larger than others and seems to be flaring away from his body. I checked 3 other cats and none of them feel like that. He seems fine and acts normal. When I touch or rub or pet the area, no reaction.

If anybody has any idea I'll appreciate it. Of course, I'll take him to the vet but I'd like to know what I'm taking him in for.

What position was he in when you felt him? I believe that the last rib is a floating rib- that means if your cat bends it can and does stick out at times.  My cat was on my lap the other day and I could feel his rib between my fingers and it does feel like there is some flexibility there.  The only reason I noticed it was that it was "sticking out" compared to his other ribs.

Just make sure there are no lumps or anything else going on. A cancerous lumps could press the rib out

Thank you for this most helpful response. He was semi-crouched and I think we just had a flash of paranoia. 

I read your response to him and he just rolled his eyes at me.

Yes the last rib is a "floating" rib - I always thought this was normal in most mammals.  Even my own last ribs stick out like that a bit.

I don't think you need to worry about it; but of course you can try the vet just to be sure

Thank you or that info my very own kittens ribs stick out and we have been very worried