Q: Our son collects pennies and was dismayed to get home from school today and find that our new puppy, Lincoln, had knocked over his penny jar. Hundreds of pennies were scattered over his bedroom floor, but I am more concerned that Lincoln may have eaten some. Are ingested pennies dangerous? A: Yes, for two reasons. Coins can block the gastrointestinal tract, especially in a small dog. If that happens, Lincoln may stop eating and start vomiting. More likely, though, his stomach acid will dissolve the pennies’ copper coating, exposing their zinc core. Since 1982, what we see as copper pennies have contained only 2.5 percent copper and 97.5 percent zinc. While a trace amount of zinc is necessary for many physiologic functions, a penny contains enough to be toxic. The veterinary literature reports deaths after an 11-pound dog ate two pennies and even after a 50-pound dog ate a …