Iron supplements and hand warmers in Pets

Iron tablets and prenatal vitamins can cause vomiting, bloody diarrhoea and liver damage in pets. How to work out the elemental iron dose and when to call.

What It Is

Iron is an essential trace mineral required for haemoglobin synthesis, myoglobin function, and cellular enzyme systems. The body has no physiological mechanism for active iron excretion; iron balance is regulated entirely at the level of intestinal mucosal absorption. When massive amounts of soluble iron are ingested, normal mucosal barrier mechanisms are overwhelmed. Free unbound elemental iron enters the systemic circulation, catalyzing the generation of toxic free radicals, triggering lipid peroxidation, and causing widespread necrosis of the gastrointestinal tract, liver, and cardiovascular system.

Where Pets Come Across It

Sources include human iron supplements (such as ferrous sulfate, ferrous gluconate, and ferrous fumarate tablets), prenatal multivitamins, chewable children's vitamin gummies with iron, lawn moss killers containing iron sulphate, and single-use disposable hand warmers or food oxygen absorber sachets containing powdered iron.

Which Animals Are Affected

Dogs are most frequently affected due to their willingness to chew open plastic multivitamin bottles, eat sweet children's vitamin gummies, or tear into discarded hand warmers. Cats are equally sensitive to iron toxicosis, but rarely consume iron tablets unless crushed or mixed into food.

Published Toxic Dose

Toxicity depends on the amount of elemental iron, not the weight of the tablet or iron salt. Ferrous sulfate is about 20% elemental iron, ferrous gluconate about 12% and ferrous fumarate about 33%; many labels list elemental iron directly. Merck advises that ingestion of more than 50 mg/kg of elemental iron generally warrants decontamination by a vet, and that more than 80 mg/kg needs further treatment and monitoring.

Signs and How Soon They Appear

Merck notes that signs usually start within 6 hours: vomiting and diarrhoea, with or without blood. They can be followed 12–24 hours later by shock, depression, fever, acidosis and liver failure, often after a period when the pet seems to recover. That apparent recovery is not a reason to skip the vet.

What to Do Right Now

Contact your veterinary clinic or a pet poison helpline immediately with the product packaging to determine the exact elemental iron content. Activated charcoal does not bind iron and is ineffective. If the ingestion occurred recently and the pet is asymptomatic, a veterinarian may perform gastric decontamination or whole bowel irrigation. In severe overdoses, hospitalisation for intravenous fluids, gastroprotectants, and specific chelation therapy with deferoxamine is required.

Hand warmers and oxygen absorbers

Pet Poison Helpline lists some hand warmers, foot warmers and the oxygen absorber sachets packed with jerky and rawhide treats among the sources of iron it sees. The amount of iron varies between products and the label rarely gives it, so a poison line will usually ask for the brand and how many packets were eaten. The packet itself can also cause a blockage in a small dog, so keep it and bring it to the vet.

Frequently Asked Questions

Sources and References

• Merck Veterinary Manual: Toxicoses From Human Multivitamins and Supplements
• Pet Poison Helpline: Iron

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