First report of changes in leukocyte morphology in response to inflammatory conditions in Asian and African elephants (Elephas maximus and Loxodonta africana).

Nicole I Stacy,Ramiro Isaza,Ellen Wiedner,Esther Lutgens

doi:10.1371/journal.pone.0185277

Abstract

Although the hematology of healthy elephants has been well-described, published information on hematological changes during disease is limited. The objective of this study was to describe qualitative morphological changes in the leukocytes of Asian and African elephants (Elephas maximus and Loxodonta africana) diagnosed with a variety of inflammatory conditions. Twenty-five of 27 elephants had morphological changes in their leukocytes, although only 16 of these had a concurrent inflammatory leukogram. Morphological changes included heterophil left-shifting with or without concurrent dysgranulopoiesis, toxicity, or hypersegmentation, reactive lymphocytes, plasma cells, and/or vacuolated monocytes. Although the observed leukocyte morphological changes are non-specific, their early recognition upon blood film evaluation may provide important, clinically-relevant information, particularly if the leukogram is normal. This case series is the first description of qualitative morphological changes in the leukocytes of elephants in association with inflammation.

Highlights

The complete blood count (CBC) is an essential part of the minimum baseline diagnostics in Asian (Elephas maximus) and African (Loxodonta africana) elephants managed in human care
The white blood cell (WBC) count from the analyzer was used for the calculation of absolute WBC numbers based on a 200 WBC differential by blood film evaluation
Three elephants died of their medical problems and included an African elephant that developed metritis sepsis due to a retained fetus, an Asian elephant with metastatic ovarian adenocarcinoma, and an Asian elephant with endotheliotropic herpesvirus (EEHV) (Table 1)

Summary

Introduction

The complete blood count (CBC) is an essential part of the minimum baseline diagnostics in Asian (Elephas maximus) and African (Loxodonta africana) elephants managed in human care. Like other members of the Afrotheria, especially the well-studied hyraxes and manatees possess leukocytes with several unique features These include having heterophils instead of neutrophils and a unique monocyte type with a bilobed—but sometimes tri-lobed—nucleus and peroxidase-positive cytoplasmic staining. This unique monocyte is observed in addition to the typical monocyte type of other mammals [1,2,3]. Monocytes represent the most abundant leukocyte type in elephants [1,2]

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Conclusion