I started feeding Gracie blueberries as an occassional snack. When I was eating some blueberries recently, one fell off my plate and rolled across the floor. Gracie gobbled it up and made it clear she wanted more.
I never felt inclined to include fruits in Gracie's Doggie Chef meals. I think they contain too much sugar for regular consumption. Yet I know Gracie thinks some fruits taste really good (she loves dates). And many fruits, like blueberries, are considered health-enhancing superfoods. So blueberries are now on Gracie's occassional snack food list (click here to see a post about other snacks Gracie enjoys).
I did some Internet research and didn't find any reputable sources claiming blueberries are bad for dogs. In "Dr. Pitcairn's Complete Guide to Natural Health for Dogs & Cats (see my review of that book here)," blueberries are recommended for occassional snacking. Any produce I give Gracie (or eat myself) is thoroughly washed first. When I share bluberries with Gracie I give her no more than three or four.