Variation in hematologic and serum biochemical values of belugas (Delphinapterus leucas) under managed care.

Blood analytes are critical for evaluating the general health of cetacean populations, so it is important to understand the intrinsic variability of hematology and serum chemistry values. Previous studies have reported data for follow-up periods of several years in managed and wild populations, but studies over long periods of time (>20 yr) have not been reported. The study objective was to identify the influences of partitioning characteristics on hematology and serum chemistry analytes of apparently healthy managed beluga (Delphinapterus leucas). Blood values from 31 managed belugas, at three facilities, collected over 22 yr, were assessed for seasonal variation and aging trends, and evaluated for biologic variation among and within individuals. Linear mixed effects models assessed the relationship between the analytes and sex, age, season, facility location, ambient air temperature, and photoperiod. Sex differences in analytes and associations with increasing age were observed. Seasonal variation was observed for hemoglobin, hematocrit, mean corpuscular volume, monocytes, alkaline phosphatase, total bilirubin, cholesterol, and triglycerides. Facilities were associated with larger effects on analyte values compared to other covariates, whereas age, sex, and ambient temperature had smaller effects compared to facility and season. Present findings provide important baseline information for future health monitoring efforts. Interpretation of blood analytes and animal health in managed and wild populations over time is aided by having available typical levels for the species and reference intervals for the degree to which individual animals vary from the species average and from their own baseline levels during long-term monitoring.