Rascal (orange tabby) was all muscle and taut until I had him altered. Right after that I shortly noticed his fat bags when he ran. Yes, it is funny and it wobbles back and forth.

He is pretty sensitive about it too.... doesn't like me to rub his belly that low.

The vet said it was FAT! Right in front of him - gosh he was embarrassed. So we have him on a Science Diet W/D formula and he is trimming down some.