Your cat has an empty sack on the bottom of its stomach?

Is your cat a SPAYED female ? If she is, it's most likely the well known 'ponch' that occurs after spaying - she'll have it for life and it's not a medical problem - It's like a flabby area of loose skin at the bottom of the tummy, seen best when she's standing on all fours. If your cat is not a spayed female, and you've recently noticed this 'empty sack' on the belly of your cat, then it's sounds like a visit to the vet is in order. Good luck with your kitty !