I don't think you'd need much, Lori. Just start with a teaspoon added to her food to see if it will entice her to eat. Or let her lick a little off your finger first and then set down her bowl with a little PB added. I'm not sure what a good food would be for an older, smaller dog Lori. Lots of great senior formulas out there, ones for pups with all sorts of issues, e.g. allergies, digestive troubles, etc. If you have a good specialty pet store that carries those ultra premium foods by you, I'd ask the manager for suggestions. They usually know a lot about the different products available. Does Disney like cottage cheese? You might try that. It has a high water content in it as well.