Ingested Pennies Are Toxic to Pets

While a trace amount of zinc is necessary for many physiologic functions, a penny contains enough to be toxic to dogs. (ponpimonsa_bibi/Shutterstock)

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 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.

Q: Some of the apartments in my complex are infested with bedbugs, so the entire apartment complex will be sprayed by a professional exterminator. I’m planning to board my cat overnight and return with her the next day.

My question is whether the bedbugs will remain on my cat and reinfest my apartment when we return. I apply flea preventive to her skin every month. Should I do something else for the bedbugs?

A: Bedbugs live in the environment, not on pets, so your cat will not carry bedbugs back into your apartment.

They climb onto their host—almost always a human rather than a pet—and feed on their blood for less than 10 minutes. Then they leave the host to return to crevices in beds and other furniture.

Treating your cat with a flea preventive is a good idea. You don’t need to apply anything else for bedbugs.

If you want to be especially cautious, remove the fabric liner or towel from your cat’s carrier before you take her from the apartment. If it’s old, dispose of it in a sealed plastic bag labeled “bedbugs.”

If you prefer to keep it, carry it to the laundry in a plastic bag so you don’t spread any bedbugs that may be hiding there. Wash your cat’s carrier bedding in hot water. If it can’t be washed, put it in a clothes dryer set on high for 20 minutes.

That should take care of it, but if your cat ever starts to scratch or lick herself, make an appointment for her to see her veterinarian.