This bowl can be used for cats or dogs and has a moat around it so that you can pour water on the moat to prevent ants and other bugs from getting to your pet's food.
I would advise to use a very low infill (say, 5% - zero will not work) and then filling it with pebbles as you print, for it to have some weight; this might be needed because pets have that tendency to keep pushing things around. I myself modelled this object after a metal bowl I have which is quite heavy for this exact reason.
I made this in inkscape, imported into openscad, then rotate_extruded it to get its shape.
WARNING: Please take notice that this is only an experiment. These bowls are very easy and cheap to find here in Campinas, Brazil, and they come as metal bowls with special coating. However, neither printed PLA nor ABS is food-safe due to the small cervices that serve as an habitat for potentially harmful bacteria. The 'moat' on my bowl is where you pour water or any other liquid, and bacteria will flourish in the small droplets of water. If you insist on using it for your cats, I would suggest giving it an acetone vapor bath, since is smooths the surfaces and seem to close the small crevices (I am not sure if it does).