Zinc Toxicity in Dogs: Common Cents Caution for Pets

Humans aren’t the only species with money troubles. As it turns out, 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 these type of symptoms, including infectious disease, immune-mediated disease, inflammatory disease and toxins, just to name a few.

Their pet parent 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: The dog ate 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.

As in this case, you might not know what your dog ingested. Symptoms may show within a couple hours to a couple days after ingestion. If you think your dog ate something dangerous call your vet immediately or the ASPCA Poison Control Hotline (888) 426-4435, or National Pet Poison Helpline (800) 213-6680.

Common Zinc Toxicity Signs

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)

• Anemia

Sources of Zinc

Since many pet parents don’t realize that zinc is harmful, they might not be aware of some of the common ways pets have access to it. Beyond pennies, other potential sources of zinc include hardware such as nuts and bolts, dietary supplements, and zinc oxide–based skin creams, such as diaper rash ointment and sunscreen.

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.

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 zinc toxicity syndrome and do not realize that pennies swallowed by dogs are far more dangerous than a “simple” foreign body. As always, prevention is best.