Abstract

Iron-positive inclusions (aka siderocytes, siderotic granules, or Pappenheimer bodies) are visible as loose focal aggregates of fine granular inclusions in erythrocytes by routine hematology stains and positive-staining with Prussian blue; they have been documented in many mammalian species and are considered a pathologic finding.¹ These inclusions are consistent with iron-laden mitochondria and have been associated with excess iron tissue stores, hemolytic anemia, toxins (e.g., lead and zinc), drugs (e.g., chloramphenicol), nutritional deficiencies (e.g., copper, pyridoxine), inflammatory disease, bone marrow disorders, neoplasia, and unknown causes.^1,2 To date, these inclusions have not been documented in any non-mammalian species. The objective of this study was to describe two cases of loggerhead sea turtles (Cc) with pale, basophilic erythrocyte inclusions that stained positive with Prussian blue, consistent with siderocytes. Both Cc were admitted due to chronic debilitation with severe anemia, emaciation, and heavy epibiota coverage. Unusual small, round, and pale basophilic erythrocyte inclusions were observed after admission at three weeks and three months, respectively. Since the morphology of these inclusions was different from degenerate organelles by routine stain, and resembled mammalian siderocytes, Prussian blue stain was performed and resulted in a positive reaction. The inclusions were observed for two and three weeks, respectively, and occurred during erythroid regeneration. Both turtles received similar treatments, including iron, metronidazole, and amikacin. Both animals were rehabilitated and successfully released. Main considerations for the presence of siderocytes in these turtles included drug effects (e.g., from metronidazole on bone marrow) and hemolytic anemia, respectively; additional differentials were excess iron, inflammatory disease, nutritional deficiencies, or a combination of all listed.³ Although a specific cause was not definitively determined in these two loggerhead patients, this is the first report of siderocytes in a non-mammalian species.

Acknowledgements

The authors wish to thank the rehabilitation staff at the Georgia Sea Turtle Center for the care of these two turtles and the University of Florida Histopathology Laboratory for technical assistance with special stains.

* Presenting author
+ Student presenter

Literature Cited

1.  Stockham SL, Scott MA. 2008. Fundamentals of Veterinary Clinical Pathology. Ames: Blackwell Publishing:142 p.

2.  Harvey JW. 2012. Veterinary Hematology: A Diagnostic Guide and Color Atlas. St. Louis: Elsevier Saunders:80–82.

3.  Weiss DJ. 2005. Bone marrow necrosis in dogs: 34 cases (1996–2004). Journal of the American Veterinary Medical Association. 227(2):263–7.