The formation of hemoglobin in the anemic dog takes place at a very rapid rate. Radio-iron is detectable in the circulating red cells 4 hours after feeding. The absorbed labelled iron is entirely converted into hemoglobin within 4 to 7 days under standard anemic conditions.
When red cell production has been accelerated by iron feeding or diet factors or when the dose of iron is very small, the dog can turn out as hemoglobin almost all the absorbed radio-iron in 2 to 3 days.
In general, absorption of radio-iron as shown by utilization to form hemoglobin in anemic dogs is more efficient in small doses in single feeding experiments. As the iron intake is increased the percentage absorption rapidly falls.