[Georgiapeach]

You should be able to feel the dog's rib's and backbone, but they should not be visible. Up the food portion if she's cleaning her bowl and she starts feeling too thin. Conversely, decrease the portion if you start feeling too thick of a fat pad around her ribs.

Is there a reason you're only feeding canned food? She'll need something hard to help keep her teeth from accumulating too much plaque. Canned food is usually used as a mix-in, rather than a total diet.