Jim, Nandina domestica does have toxic potential, as the berries and leaves contain cyanogenic glycosides. Depending on the circumstances of exposure, this can cause vomiting, diarrhea, a lack of oxygen in the blood, decreased heart rate, respiratory congestion, seizures and coma. If large enough amounts are ingested, this could ultimately lead to respiratory failure and death. While most problematic ingestions involve large animals who graze on substantial quantities of the plant, we would still recommend not allowing your dog to chew on Nandina berries or leaves.