How to tell if a dog ate a screw?

Let's see I left them in the house at around 2 or 230 pm and came back at around 5:45 and there was a loaf of bread that was eaten and two boxes of screws that were ripped open. I doubt either of them ate either on the count of they are picky eaters. Also, another loaf of bread was taken down but they didnt open it. She hasnt eaten all of her food yet but that's normal for her she just snacks on it and saves it (idk) but I just gave her a dog biscuit which she ate with little trouble and actually stole my other dog's treat. Does she sound fine?