Abstract

Blood is routinely collected from Florida manatees (Trichechus manatus latirostris) during health assessment studies, in clinical evaluation of ill or injured patients, for out-of-water monitoring, and for research studies.^1-3 During health assessment studies of clinically normal manatees over 12 years, erroneous high white blood cell (WBC) counts in 32 of 904 blood samples (4%) were observed using the laser flow cytometry-based ADVIA 120 hematology system with multispecies software. The ADVIA 120 uses two methodologies for obtaining WBC counts: the basophil channel and the peroxidase channel—the former of which is routinely used for WBC count reporting. Of the 32 identified erroneous WBC counts, the mean was 66.61±54.02x10³/µl (range 5.80–211.30x10³/µl), which was above the acceptable 10% variation and up to 21 times higher than the peroxidase channel with a mean of 6.07±2.83x10³/µl (range 2.32–17.58x10³/µl). Cytograms of the basophil channel showed an artifact in areas that typically identify lymphocytes, monocytes, and heterophils. Blood film evaluation revealed frequent, large platelet clumps similar in size to WBC, indicating that platelet clumps were counted as WBC using this methodology, also reflecting significantly lower platelet counts by the ADVIA 120. Given that blood withdrawal occurred without difficulty in these cases and during summer as well as winter captures (i.e., independently of environmental temperatures), sampling conditions unique to manatees may cause these erroneous numbers. These findings show the importance of critically evaluating hematological data, as the described artifact can alter hematology data and clinical interpretations of an individual and of population-based reference intervals.

Acknowledgements

The authors wish to thank the capture and assessment teams of the U.S. Geological Survey, the Florida Fish and Wildlife Conservation Commission, and the University of Florida Aquatic Animal Health Program. All research was conducted under USFWS research permits issued to the USGS, FWC, and UF and under approval of IACUC sample collection standards for wildlife.

*Presenting author
+Student presenter

Literature Cited

1.  Bonde RK, Aguirre AA, Powell J. 2004. Manatees as sentinels of marine ecosystem health: are they the 2000-pound canaries? EcoHealth. 1(3):255–262.

2.  Stamper MA, Bonde RK. 2012. Health assessment of captive and wild-caught West Indian manatees (Trichechus manatus). In: Sirenian Conservation: Issues and Strategies in Developing Countries. Gainesville, FL: University Press of Florida; pp. 139–147.

3.  Harvey JW, Harr KE, Murphy D, Walsh MT, Nolan EC, Bonde RK, Pate MG, Deutsch CJ, Edwards HH, Clapp WL. 2009. Hematology of healthy Florida manatees (Trichechus manatus). Vet Clin Pathol. 38(2):183–193.