Why is it risky?
Modern coins in many countries contain high levels of zinc (US pennies minted after 1982 are 97.5% zinc, and many European and international coins use zinc alloys). When a zinc-containing coin is ingested and exposed to gastric acid, zinc dissolves and is absorbed, causing intravascular hemolysis (red blood cell destruction) and multi-organ failure affecting kidneys, liver, and the cardiovascular system.
Affected Systems
Digestive · Kidneys · Liver · Cardiovascular
Symptoms
Vomiting, diarrhea, lethargy, weakness, pale or yellowish gums (hemolytic anemia), reddish-brown urine, progressive kidney and liver failure.
What To Do
Emergency vet. X-ray to locate coin. Endoscopic or surgical removal is typically required, do NOT wait for the coin to pass naturally. IV fluids and treatment of resulting anemia.
Notes
Additional zinc sources: zinc-coated hardware (galvanized screws, nuts, bolts, wire), zinc-alloy die-cast toys, some jewelry, zinc oxide cream (diaper rash cream, sunscreen). Cats can contact zinc oxide cream through grooming areas where owners applied it, even topical exposure in significant amounts causes toxicity via grooming ingestion. Keep all zinc oxide products secured.
Sources
→ ASPCA Animal Poison Control Center — aspca.org
→ Merck Veterinary Manual — merckvetmanual.com
→ Pet Poison Helpline — petpoisonhelpline.com/poison/zinc/