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As far as iron toxicity is concerned, the dose that she got is what is going to determine whether or not she has clinical signs and how soon we see them. As much as 20-40mg/kg iron can result in a toxicosis although doses at greater then 60mg/kg are considered more likely to be very serious. Best ting you can do is have your vet run an Iron level in the blood to determine if intervention is necessary. This may include surgery or chelation therapy. Dogs appear to be more resistant to iron toxicity than people and it depends on the type of iron that is ingested.
Likely you would have started to see the side effects at this point, but I would continue with the high fiber (maybe add in some bread as well) and hope that those little fragments pass through.
I hope that helps!