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Swallowing a Penny Comes at a High Price for Dogs
Common cents caution for pets

Humans aren’t the only species with money troubles. Did you know that pennies can be hazardous to your dog’s health? One-cent coins used to be made from 100 percent copper, which is nontoxic. In 1982, the government began minting pennies that were made mainly from zinc (much cheaper) and coated them with a thin layer of copper, keeping the look of a penny. When swallowed, the copper coating of the newer penny dissolves in the stomach acids, leaving a wafer of toxic zinc.

A few years back I saw a dog who had been vomiting for two days and his blood work revealed both anemia (low red blood-cell count) and elevated kidney values. There are many causes for this type of presentation, including infectious disease, immune-mediated disease, inflammatory disease and toxins, just to name a few.

His owner had no idea if he’d eaten anything out of the ordinary. X-rays revealed a round metallic object in the stomach. You guessed it, a penny. The penny was removed non-surgically with an endoscope, and the dog recovered during the course of the week with intensive supportive care—a very expensive penny.

The clinical signs and potential problems caused by zinc toxicity include:

  • vomiting and diarrhea,
  • blood-tinged urine,
  • icterus (yellow mucous membranes including gums and the “whites” of the eyes),
  • liver failure,
  • kidney failure,
  • hemolysis, which is the destruction of red blood cells (how zinc produces hemolysis is not known),
  • anemia.

Treatment:

If an object possibly made of zinc is seen on a radiograph, it should be removed promptly. Supportive care then becomes crucial and includes fluid therapy to keep circulation to the kidneys adequate, helping to prevent failure. A blood transfusion may be necessary to combat anemia. Anti-nausea medications are indicated, as well as stomach protectants (antacids and “coating” medications), due to the corrosive nature of zinc. Researchers are still actively looking at methods for binding excess zinc in the circulation, similar to the way lead poisoning is treated, but this is not yet available.

Other sources:

Other sources of zinc include hardware, such as nuts and bolts, dietary supplements, and (surprisingly) zinc oxide–based skin creams, such as diaper rash ointment and sunscreen.

Prevention of zinc toxicity:

  • In addition to coins, be mindful of the nuts and bolts on your dogs’ kennels, as they may contain zinc.
  • Do not use ointments and creams on the fur or skin of your pet, unless directed by your veterinarian, as these usually get licked off, potentially causing toxicity.
  • Keep vitamins, dietary supplements and topical creams far out of your pets reach.

Many people are unaware of this syndrome and do not realize that pennies are far more dangerous than a “simple” foreign body. This is a recently described disease process and many questions are still unanswered. As always, prevention is best: ”Penny wise, pound foolish” has a whole new meaning.

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Veterinarian Shea Cox has enjoyed an indirect path through her professional life, initially obtaining degrees in fine arts and nursing. She later obtained her veterinary medical degree from Michigan State University in 2001 and has been practicing emergency and critical care medicine solely since that time. In 2006, she joined the ER staff at PETS Referral Center in Berkeley and cannot imagine a more rewarding and fulfilling place to spend her working hours. In her spare time, she loves to paint, wield her green thumb, cook up a storm and sail. Her days are shared with the three loves of her life: her husband Scott and their two Doberman children that curiously occupy opposite ends of the personality spectrum.

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