Chronic iron overload causing haemochromatosis and hepatopathy in 21 horses and one donkey

Abstract

BACKGROUND\nIron toxicosis is rarely reported in horses and chronic excessive oral iron intake has not been reported to cause clinical symptoms in equids.\n\n\nOBJECTIVES\nThis case series describes 21 genetically unrelated horses and one donkey with chronic iron overload causing haemochromatosis and hepatopathy.\n\n\nSTUDY DESIGN\nCase series.\n\n\nMETHODS\nAll equids showing clinical signs compatible with chronic liver disease presented to Utrecht University and diagnosed with iron overload and haemochromatosis based on histopathological evaluation of liver tissue and/or blood transferrin saturation levels of >80% and proof of excess dietary iron intake due to excess iron content in drinking water were included.\n\n\nRESULTS\nThis study included 22 equids. All tested animals (n\xa0=\xa019) had transferrin saturation >80% and 21 of 22 had increased gamma-glutamyltransferase (γGT). Ultrasonography revealed rounded liver margins in five out of six horses and increased echogenicity in 4/6. Histological examination of liver tissue of 12 animals showed hepatitis, fibrosis and haemosiderin accumulation in macrophages and hepatocytes. Post-mortem examination also revealed haemosiderin accumulation in other organs in all seven examined animals. High iron content in drinking water was identified as the source of iron overload in all cases. All animals were housed under the same conditions for a minimum of 9\xa0years prior to diagnosis of haemochromatosis. Of 22 animals, 13 survived until 1 January 2018, ranging from 17 to 79\xa0months post diagnosis.\n\n\nMAIN LIMITATIONS\nHistology of liver tissue was not available for 10 of 22 cases.\n\n\nCONCLUSIONS\nChronic iron overload can lead to haemochromatosis and hepatopathy in equids. Development of disease is slow and clinical signs are nonspecific. Long-term excessive iron intake in equids should be avoided. If animals drink from natural water sources, it is important to test the water for iron content. The Summary is available in Spanish - see Supporting Information.