Chronic iron overload causing haemochromatosis and hepatopathy in 21 horses and one donkey.
Authors: Theelen M J P, Beukers M, Grinwis G C M, Sloet van Oldruitenborgh-Oosterbaan M M
Journal: Equine veterinary journal
Summary
# Editorial Summary: Iron-Induced Haemochromatosis in Horses and Donkeys Whilst iron toxicosis is well-documented in other species, clinical haemochromatosis from chronic oral iron intake has never been reported in equids—until this case series of 22 animals (21 horses, one donkey) presenting with liver disease. All cases shared a common exposure: elevated iron content in drinking water at their facilities, with animals housed under identical conditions for a minimum of nine years before diagnosis. Laboratory and histopathological findings were consistent across the cohort, with transferrin saturation exceeding 80% in all tested animals (n=19), elevated gamma-glutamyltransferase in 21 of 22, and hepatic biopsy specimens (n=12) demonstrating hepatitis, fibrosis and haemosiderin accumulation in both macrophages and hepatocytes; post-mortem examination of seven animals further revealed haemosiderin deposition in multiple extrahepatic organs. Survival times post-diagnosis ranged considerably (17–79 months), with 13 of 22 animals surviving beyond 18 months, though the insidious nature of the condition—characterised by nonspecific clinical signs—likely resulted in delayed recognition in many cases. For practitioners managing horses with access to natural water sources or bore water, this case series underscores the importance of testing water iron content as part of differential diagnosis for chronic hepatopathy, and highlights a previously unrecognised but clinically significant toxic pathway in equine medicine.
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Practical Takeaways
- •Test drinking water for iron content, especially from natural water sources, as chronic excessive iron intake can cause irreversible liver disease in horses and donkeys
- •Clinical signs of iron-induced hepatopathy are nonspecific and slow to develop; suspect iron toxicosis in cases of chronic liver disease with unexplained hepatic dysfunction
- •Transferrin saturation >80% and elevated GGT are useful diagnostic markers; consider liver biopsy if histological confirmation needed, as post-mortem findings showed haemosiderin accumulation in multiple organs
Key Findings
- •22 equids (21 horses, 1 donkey) developed haemochromatosis and hepatopathy from chronic iron overload via drinking water
- •All 19 tested animals had transferrin saturation >80% and 21/22 had elevated gamma-glutamyltransferase
- •Histological examination of 12 animals showed hepatitis, fibrosis, and haemosiderin accumulation in macrophages and hepatocytes
- •All animals were housed under identical conditions for minimum 9 years; 13 of 22 survived >17 months post-diagnosis