Effect of oral administration of excessive iron in adult ponies.

This study was conducted to examine whether giving ponies large amounts of dietary iron could lead to liver damage, similar to conditions observed in horses with potential iron overdose or hemochromatosis. The research found that while iron levels in the liver and serum increased after eight weeks of iron supplementation, no pathological changes or adverse clinical symptoms related to iron toxicosis were observed in the ponies.

Objective and Methodology

• The goal of the study was to determine whether surplus dietary iron could cause liver damage in ponies, akin to that seen in horses with potential iron overdose or hemochromatosis.
• For the experiment, six adult male ponies were chosen, of which four received 50 mg of iron/kg body weight daily in the form of ferrous sulfate administered orally. This iron supplement was given mixed with applesauce. The remaining two ponies acted as controls, receiving only applesauce.
• Different tests were carried out on both blood and hepatic tissue, including complete blood counts, serum biochemical analyses, tissue biopsies, and serum iron concentration measurements.
• Samples were collected several times: at the start of the experiment, two days into the experiment, and at the end of weeks 1, 3, 6, and 8. The treatment was stopped after eight weeks.

Results

• The study found that by the eighth week, hepatic iron concentrations, the percentage of transferrin saturation, serum ferritin concentrations, and serum iron concentrations had increased compared to the baseline and control measurements.
• Importantly, despite the increased iron concentrations, no negative clinical signs or histologic lesions in the liver were detected in any of the ponies, indicating no evidence of iron toxicosis.
• The study found that 20 weeks after the discontinuation of the iron supplement, hepatic iron concentrations had decreased.

Conclusions

• The researchers concluded that it was unlikely for iron toxicosis to develop in adult ponies or horses during a period of less than eight weeks when food or water contained increased amounts of iron.
• The study raises doubts about previous reports which linked hemosiderin build-up (a form of iron) in animals to iron toxicosis, suggesting instead that it might be a symptom of a primary liver disease with secondary hemosiderin accumulation, particularly if the only source of excess iron is oral consumption.