Iron deficiency anemia is a common finding in many domestic animals. In adult animals, it is usually due to chronic blood loss associated with gastrointestinal parasites. In neonates, it is even more common and is most likely due to inadequate iron intake. The iron content of maternal milk is low and does not meet the needs of rapid growth. This is exacerbated in unweaned piglets raised indoors, with no access to soil or other sources of iron. Even piglets raised outdoors may need supplementation. There are economic losses associated with this condition because the piglets fail to thrive, don't gain weight, and may even die. Some cases of iron toxicity secondary to supplementation have been reported.
The most common finding in iron deficiency anemia is microcytosis. Smaller-than-normal erythrocytes are produced when insufficient hemoglobin is contained in developing erythrocyte precursors. The erythrocytes go through additional cell division to achieve a minimum hemoglobin concentration within the cell. If iron stores are sufficiently low, the concentration within the RBCs will be lower, which leads to paler (hypochromatic) cells. The small, pale cells are also more fragile, leading to fragmentation and formation of schistocytes and acanthocytes. Other changes commonly seen are neutropenia, which is typically associated with a concurrent lymphopenia causing leukopenia (but not in this case).
Thromobocytosis may also be seen. There are generally no biochemical changes related to this condition. Definitive diagnosis requires testing iron stores. Serum iron is usually decreased. The total iron-binding capacity (TIBC) is increased in pigs, horses, and ruminants. Serum ferritin is usually decreased but requires a species-specific assay that is not commercially available for pigs. Tissue levels of iron (in bone marrow, liver, or spleen) can also be measured.
Links to sections in the MVM:
Anemia in Animals
Nutritional Deficiency Anemia in Animals
Overview of Health-Management Interaction: Pigs
Nutritional Requirements of Pigs
Overview of Iron Toxicity in Newborn Pigs
References
Knight LC, Dilger RN. Longitudinal Effects of Iron Deficiency Anemia and Subsequent Repletion on Blood Parameters and the Rate and Composition of Growth in Pigs Nutrients. 2018 May 17;10(5). pii: E726.doi: 10.3390/nu10050632
Staroń R, Van Swelm RP, Lipiński P, et al. Urinary Hepcidin Levels in Iron-Deficient and Iron-Supplemented Piglets Correlate with Hepcidin Hepatic mRNA and Serum Levels and with Body Iron Status. PLoS One. 2015 Aug 31;10(8): e0136695. doi: 10.1371/journal.pone.0136695
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