Cat Has Foul Odor Coming From Mouth. What Could It Be?

Your cats foul odor could be a number of things happening.  I think the first thing to consider is she may have an abscessed tooth - if you notice any swelling on either of her cheeks.  Or she just may have a bad tooth that is rotten.  Another indication of bad breath could be pancreatitis (my dog has the worst smelling breath and it turned out she had pancreatitis - but you would also notice things like your cat losing weight).

  It could be the cat has some soreness inside his/her mouth, it's like smelling the puss and that stuff, same goes for horses. I would probably check it out and if there was something wrong, then I would bring her to the vet! Hope this helps, Good luck, :)