Ooh! It's great that your going to make them! I think adding hay dust is okay as long as it still has a dough like consistency (I haven't actually tried, so if it goes horribly wrong, don't blame me!). They last for about 2 weeks in an air tight sealed container. It makes about 25 (give or take) one teaspoon treats, I have 20 one teaspoon treats, and made a large treat (about 1 1/4 tablespoon) for a photo shoot! I hope all goes well!I'm going to make these for Theo today! I had already planned on making him some treats, but I couldn't find a recipe. I think I'm going to add hay dust, do you think that is a good idea? How long do these last in the fridge? How many treats does this recipe make?