Ask the Vet: Ingested Pennies Toxic to Pets
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% copper and 97.5% 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 single penny.
Zinc is also hidden in an astonishing range of products: the hardware on dog crates and carriers, galvanized cages and bowls, jewelry, toys, board game pieces, zinc-coated tinsel and garland, denture adhesives, sunscreen and diaper rash creams.
After ingesting excessive zinc, dogs experience vomiting, diarrhea, anorexia, lethargy and weakness. These clinical signs may occur within a few hours of ingestion or, in the case of pennies, be delayed up to three to seven days while stomach acid dissolves the coins.
Within days, the zinc destroys the dog's red blood cells, causing a condition called hemolytic anemia. "Hemo-" refers to blood, and "-lytic" means to break apart. This destruction results in anemia, or abnormally low numbers of the red blood cells that carry oxygen throughout the body.
If it goes this far, you may notice dark urine and a yellow tinge to Lincoln's skin, gums and whites of his eyes.
To prevent hemolytic anemia, I recommend you take Lincoln to his veterinarian immediately for evaluation, which will probably include radiographs, or X-rays, to determine whether his gastrointestinal tract contains coins. In addition, make sure your son secures his penny jar with a lid.
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