• Iron Iron is an essential mineral. When not protein bound in the body, it is highly reactive, induces free radicals and is damaging to tissues.
• There are numerous forms of iron including:
  • Iron-containing supplements and multivitamins. Injectable iron therapy is also a potential source although this is rare in dogs and cats.
  • Some moss killers contain ferrous sulfate.
  • Some slug and snail killers contain ferric phosphate, generally 1% for domestic products and 3% for professional products. Iron (III) ethylenediaminetetraacetate is also used as a slug killer in some countries.
  • Oxygen absorbers or deoxidizer sachets used as preservatives in dried foods.
  • Iron-containing hand warmers and heat patches (for pain relief).
  • The remainder of this article will discuss toxicity from ingesting excessive amount of iron.
• There are numerous forms of iron. The soluble forms are the most toxic. Insoluble forms, such as metallic iron or iron oxide (rust), are not considered toxic. Iron oxide and hydroxides (E172) are also used in some foods and medicines as a colorant.
• Calculate the amount of elemental iron ingested to determine if the pet ingested a toxic amount of iron.
• Mild to moderate iron toxicity can occur when 20-60 mg/kg of elemental iron is ingested. Severe toxicity can occur when over 60 mg/kg elemental iron is ingested. Over 100 mg/kg elemental iron is considered fatal without prompt treatment. Note these toxic doses are based on soluble, bioavailable forms of iron and will greatly overestimate the toxicity of insoluble poorly bioavailable iron compounds.

All cases of ingestion of iron tablets should be assessed urgently.

Presenting signs

• Lethargy.
• Vomiting Vomiting.
• Diarrhea, sometimes hemorrhagic.
• Vomitus and feces may have a metallic odor.

Acute presentation

• Animals usually present with an acute onset of gastrointestinal signs. However, about 6 hours following ingestion, the gastrointestinal signs may abate and the cat may appear to recover. Without treatment, diarrhea, dehydration and coma occur about 24 hours later.
• Some cats may present with icterus.

Geographic incidence

• Iron toxicity can occur anywhere.

Age predisposition

• Iron toxicity can occur at any age.

Breed/Species predisposition

• There is no breed predisposition.

Public health considerations

• Iron can be toxic to humans if excessive amounts are ingested. Care must be taken when using products containing iron.

Cost considerations

• Moderate to expensive: therapy and cost will depend on the amount of elemental iron ingested and how quickly therapy was instituted.