Variation in Hematological and Serum Biochemical Values of Captive Belugas (Delphinapterus leucas)
IAAAM 2012
Stephanie A. Norman1; Laurel A. Beckett2; Woutrina A. Miller1; Judy St. Leger3; Roderick C. Hobbs4
1Pathology, Microbiology and Immunology Department, School of Veterinary Medicine, University of California, Davis, CA, USA; 2Division of Biostatistics, Department of Public Health Sciences, School of Medicine, University of California, Davis, CA, USA; 3Sea World San Diego, San Diego, CA, USA; 4National Marine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA, USA

Abstract

Blood analytes are a critical tool in evaluating the general health status of cetacean populations, so it is important to understand the intrinsic variability of hematology and blood chemistry values.1 Previous studies have reported data for follow-up periods of several years in captive and wild populations,2 but studies over long periods of time (> 20 years) have not been reported. This long-term dataset followed 34 captive belugas from three facility locations for up to 22 years. The main objectives of this study were to characterize the long-term trajectories and variation of hematology and serum chemistry analyte values in apparently healthy captive beluga whales (Delphinapterus leucas), to quantify variation between animals, and to examine influences of biology and environment on variation, using analytical techniques for monitoring of clinical blood values that may be applied to wild populations of marine mammals that are amenable to repeated captures for health assessments and blood sampling. A series of linear mixed effects models3 was used to describe trajectories and assess the relationship between the analytes and sex, age, season, facility location, and ambient air temperature.4,5 Individual whales showed both consistent differences from each other and variation within whale over time. Most analytes showed significant differences in mean levels between males and females and changes with age. Seasonal variation was observed for hemoglobin, hematocrit, mean corpuscular volume (MCV), monocytes, alkaline phosphatase, total bilirubin, cholesterol and triglycerides. Circannual variation patterns were similar across facilities for MCV, white blood cells, creatinine, globulin, creatinine phosphokinase, phosphorus, sodium, and chloride. Facility location was associated with the largest effects on analyte levels for both hematology and serum chemistry relative to the other covariates, while age, sex and ambient temperature had lower effects on analyte levels compared to those of facility location and season. These findings from a long-term assessment of individual variation in healthy cetaceans agree with previous reports that many blood analytes differ significantly between age groups and seasons and provide important baseline information to assist in future health monitoring efforts.6,7 Variability from factors such as sex, age, season, and nutritional status, as well as individual tendencies to track high or low, should be considered when interpreting blood analyte values and animal health in both captive and wild populations over time.

Acknowledgments

The authors thank the Sea World's clinical veterinary and laboratory staff for sample collection, analysis, and tabulation of these extensive data.

References

1.  Terasawa F, Kitamura M, Fujimoto A, Hayama S. Seasonal changes of blood composition in captive bottlenose dolphins. J Vet Med Sci. 2002;64:1075–1078.

2.  Bossart GD, Reidarson TH, Dierauf LA, Duffield DA. Clinical pathology. In: Dierauf LA, Gulland FMD, eds. CRC Handbook of Marine Mammal Medicine. 2nd ed. Boca Rotan, FL: CRC Press; 2001:383–436.

3.  Gascoyne SC, Hawkey CW. Patterns of variation in vertebrate haematology. Clin Hemorheol. 1992;12:627–637.

4.  Twisk JWR. Applied longitudinal data analysis for epidemiology. Cambridge, UK: Cambridge University Press; 2003:301.

5.  Zeger SL, Liang KY. Longitudinal data analysis for discrete and continuous outcomes. Biometrics. 1986;42:121–130.

6.  St. Aubin DJ, Deguise S, Richard PR, Smith TJ, Geraci JR. Hematology and plasma chemistry indicators of health and ecological status in beluga whales, Delphinapterus leucas. Arctic. 2001;54:317–331.

7.  Norman SA, Goertz CEC, Burek KA, et al. Seasonal hematology and serum chemistry of wild beluga whales (Delphinapterus leucas) in Bristol Bay, Alaska. J Wildlife Dis. 2012;48(1):21–32.

  

Speaker Information
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Stephanie A. Norman
Pathology, Microbiology and Immunology Department
School of Veterinary Medicine
University of California
Davis, CA, USA


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