Effects of duration of capture and sample handling on critical care blood analytes in free-ranging bottlenose dolphins

Using Blood Gas Analysis and Capnography to Determine Oxygenation Status in Bottlenose Dolphins (Tursiops truncatus) Following the Deepwater Horizon Oil Spill

Following the Deepwater Horizon (DWH) oil spill in 2010, poor pulmonary health and reproductive failure in bottlenose dolphins (Tursiops truncatus) in the northern Gulf of Mexico were well-documented. One postulated etiology for the increased fetal distress syndrome and pneumonia found in affected perinatal dolphins was maternal hypoxia caused by lung disease. The objective of this study was to evaluate the utility of blood gas analysis and capnography in determining oxygenation status in bottlenose dolphins with and without pulmonary disease. Blood and breath samples were collected from 59 free-ranging dolphins in Barataria Bay, Louisiana (BB), during a capture-release health assessment program, and from 30 managed dolphins from the U.S. Navy Marine Mammal Program in San Diego, CA. The former was the oil-exposed cohort and the latter served as a control cohort with known health histories. Capnography and select blood gas parameters were compared based on the following factors: cohort, sex, age/length class, reproductive status, and severity of pulmonary disease. Animals with moderate-severe lung disease had higher bicarbonate concentrations (p = 0.005), pH (p < 0.001), TCO₂ (p = 0.012), and more positive base excess (p = 0.001) than animals with normal-mild disease. Capnography (ETCO₂) was found to have a weak positive correlation with blood PCO₂ (p = 0.020), with a mean difference of 5.02 mmHg (p < 0.001). Based on these findings, indirect oxygenation measures, including TCO₂, bicarbonate, and pH, show promise in establishing the oxygenation status in dolphins with and without pulmonary disease.

Hematologic and serum biochemical reference intervals for free-ranging common bottlenose dolphins (Tursiops truncatus) and variation in the distributions of clinicopathologic values related to geographic sampling site

OBJECTIVE

To develop robust reference intervals for hematologic and serum biochemical variables by use of data derived from free-ranging bottlenose dolphins (Tursiops truncatus) and examine potential variation in distributions of clinicopathologic values related to sampling sites' geographic locations.

ANIMALS

255 free-ranging bottlenose dolphins.

PROCEDURES

Data from samples collected during multiple bottlenose dolphin capture-release projects conducted at 4 southeastern US coastal locations in 2000 through 2006 were combined to determine reference intervals for 52 clinicopathologic variables. A nonparametric bootstrap approach was applied to estimate 95th percentiles and associated 90% confidence intervals; the need for partitioning by length and sex classes was determined by testing for differences in estimated thresholds with a bootstrap method. When appropriate, quantile regression was used to determine continuous functions for 95th percentiles dependent on length. The proportion of out-of-range samples for all clinicopathologic measurements was examined for each geographic site, and multivariate ANOVA was applied to further explore variation in leukocyte subgroups.

RESULTS

A need for partitioning by length and sex classes was indicated for many clinicopathologic variables. For each geographic site, few significant deviations from expected number of out-of-range samples were detected. Although mean leukocyte counts did not vary among sites, differences in the mean counts for leukocyte subgroups were identified.

CONCLUSIONS AND CLINICAL RELEVANCE

Although differences in the centrality of distributions for some variables were detected, the 95th percentiles estimated from the pooled data were robust and applicable across geographic sites. The derived reference intervals provide critical information for conducting bottlenose dolphin population health studies.

A transcriptomic analysis of the stress induced by capture-release health assessment studies in wild dolphins (Tursiops truncatus)

The health of wild bottlenose dolphins (Tursiops truncatus) is typically evaluated by the study of animals that are captured and released back into the wild after examination. The impact of such studies on gene expression in peripheral blood cells was investigated using microarray and quantitative polymerase chain reaction methods. Significantly increased expression was observed in two major classes of genes: (i) energy metabolism, and (ii) responsiveness to stress and trauma, the latter effect suggesting the initiation of an acute-phase response. The value of data obtained in capture/release studies may need to be weighed against the potential physiological impacts of such studies.