Iron Poisoning (Hemachromatosis) in Horses

Published on
Last updated on
4 min read

Key takeaways

Iron poisoning is a potentially life-threatening condition that occurs when there is an excess of iron in a horse's system. 

  • Iron toxicosis can be either acute, typically caused by an overdose of iron-containing supplements, or chronic, caused by excessive accumulation of iron in the system for an extended length of time
  • Common symptoms of acute iron toxicosis include abdominal pain, reduced appetite, diarrhea, and yellow gums
  • Diagnosis is based on history of exposure, physical examination, bloodwork, and measuring iron levels in the bloodstream
  • Once diagnosed, early treatment focuses on stabilization with IV fluids and removing any undigested iron-containing material from the stomach
  • Once stabilized, treatment involves chelation therapy to bind and remove iron in the bloodstream
  • Prognosis depends on the kind of toxicosis, timing of treatment, and the extent of organ damage
Are you concerned?

Connect with a vet to get more information about your pet’s health.

Book an online vet

A closer look: Iron Poisoning (Hemachromatosis) in Horses

Iron is a micronutrient essential to maintaining healthy levels of hemoglobin in the blood. Hemoglobin is the primary functional protein in blood that carries oxygen from the lungs to the body tissues. If the concentration of iron in the blood exceeds levels needed for normal functioning, it can lead to iron poisoning.

Symptoms of iron toxicosis vary in accordance with the underlying cause. It can be further characterized as acute or chronic.

Acute iron toxicosis is typically caused by excessive ingestion of iron-containing supplements.

Left untreated, acute iron toxicosis ultimately leads to liver failure and accumulation of ammonia in the bloodstream due to impaired liver function.

Chronic iron toxicosis, also known as hemochromatosis, is a condition in which the animal's body absorbs and stores excessive amounts of iron.

Risk factors

Iron toxicosis is rare in horses. In both its acute and chronic forms, iron toxicosis is a potentially life-threatening condition warranting prompt veterinary attention.

If iron oversupplementation is suspected, immediate veterinary attention is crucial in ensuring a favorable prognosis.

Foals are more susceptible to oversupplementation due to their lower body weight, which makes the toxic dose of iron much smaller than in adult horses. Horses given iron supplements are more likely to develop iron toxicosis.

Possible causes

Causes of iron toxicosis include:

  • Overdose of iron supplements and multivitamin
  • Ingestion of excessive iron from water sources

Testing and diagnosis

A horse presenting symptoms associated with iron toxicosis generally undergoes the following diagnostics:

  • Physical exam
  • Blood tests, including testing for iron levels
  • History of supplement use or water quality testing

Steps to Recovery

Initial treatment is focused on stabilization. Supportive care involves:

  • Fluid therapy and electrolytes to ensure adequate hydration
  • Medications to protect the intestinal lining
  • Stomach lavage to remove any undigested supplement

Symptomatic treatment of iron toxicosis involves:

  • Chelation therapy (chelating agents bind to excess iron in the system and help its excretion from the body)

Currently, there is no definitive treatment for chronic iron toxicosis. Removing the source of iron and monitoring for changes in liver and cardiac function are recommended in these cases.

Prognosis for iron toxicosis varies widely, in accordance with the underlying cause, the timing of treatment, and the extent of organ damage.

Acute iron toxicosis carries a good prognosis if promptly treated in the initial stages. If medical attention is delayed or the condition is left untreated, it can lead to permanent and life-threatening liver damage.

In both acute and chronic iron toxicosis, horses that develop symptoms of hepatic encephalopathy have a poor prognosis, and many are euthanized.


Iron toxicosis is not contagious.

Acute iron toxicosis is preventable by ensuring that horses cannot access iron sources. Strategies include:

  • Administering Vitamin E and selenium supplements, which can help prevent iron toxicosis
  • Analyzing of iron content in water supplies
  • Discussing supplements with a veterinarian prior to administration
  • Only administering additional iron to horses who have a confirmed iron deficiency

Is Iron Poisoning (Hemachromatosis) in Horses common?

Iron toxicosis is a rare condition in horses.

Typical Treatment

  • Fluid therapy
  • Electrolytes
  • Gastroprotectants
  • Gastrointestinal decontamination
  • Chelation therapy


Karyn Bischoff BS DVM MS DipABVT; Birgit Puschner DipABVT PhD DVM - Writing for Vetlexicon
M J P Theelen 1, M Beukers 2, G C M Grinwis 3, M M Sloet van Oldruitenborgh-Oosterbaan 1 - Writing for Equine Veterinary Journal
Jonathan H. Foreman , DVM, DACVIM - Writing for MSD Veterinary Manual
No Author - Writing for Elsevier Science
Jean-Pierre Lavoie DVM, DACVIM - Writing for Blackwell's Five-Minute Veterinary Consult: Equine, 3rd Edition
Reed, Stephen M., and Sellon, Debra C. - Writing for Elsevier Health Sciences
M J P Theelen 1, M Beukers 2, G C M Grinwis 3, M M Sloet van Oldruitenborgh-Oosterbaan 1 - Writing for Equine Veterinary Journal
T P Mullaney 1, C M Brown - Writing for Equine Veterinary Journal
M. J. P. Theelen, M. Beukers, G. C. M. Grinwis, M. M. Sloet van Oldruitenborgh-Oosterbaan - Writing for Equine Veterinary Journal
Safdar A. Khan , DVM, MS, PhD, DABVT, - Writing for MSD Veterinary Manual

Our editorial committee

Our medical review team is responsible for validating and maintaining the quality of our medical information.