Evaluation of adrenocortical function in Florida manatees (Trichechus manatus latirostris)

Abstract

The study objectives were to determine the predominant manatee glucocorticoid; validate assays to measure this glucocorticoid and adrenocorticotropic hormone (ACTH); determine diagnostic thresholds to distinguish physiological vs. pathological concentrations; identify differences associated with sex, age class, female reproductive status, capture time, and lactate; and determine the best methods for manatee biologists and clinicians to diagnose stress. Cortisol is the predominant manatee glucocorticoid. IMMULITE 1000 assays for cortisol and ACTH were validated. Precision yielded intra- and inter-assay coefficients of variation for serum cortisol: ≤23.5 and ≤16.7%; and ACTH: ≤6.9 and ≤8.5%. Accuracy resulted in a mean adjusted R(2)≥0.87 for serum cortisol and ≥0.96 for ACTH. Assay analytical sensitivities for cortisol (0.1 µg/dl) and ACTH (10.0 pg/ml) were verified. Methods were highly correlated with another IMMULITE 1000 for serum cortisol (r=0.97) and ACTH (r=0.98). There was no significant variation in cortisol or ACTH with sex or age class and no correlation with female progesterone concentrations. Cortisol concentrations were highest in unhealthy manatees, chronically stressed by disease or injury. ACTH was greatest in healthy free-ranging or short-term rehabilitating individuals, peracutely stressed by capture and handling. Cortisol concentrations ≥1.0 µg/dl were diagnostic of chronic stress; ACTH concentrations ≥87.5 pg/ml were diagnostic of peracute stress. In healthy long-term captive manatees, cortisol (0.4±0.2 µg/dl) and ACTH (47.7±15.9 pg/ml) concentrations were lower than healthy free-ranging, short-term rehabilitated or unhealthy manatees. Capture time was not significantly correlated with cortisol; ACTH correlation was borderline significant. Cortisol and ACTH were positively correlated with lactate.

Monitoring Oral Temperature, Heart Rate, and Respiration Rate of West Indian Manatees (Trichechus manatus) During Capture and Handling in the Field

“…The high lactate concentrations are indicative of lactic acidosis as a result of muscular exertion and struggle related to the capture event (Harvey et al, 2007). Lactate concentrations are also positively correlated with cortisol and ACTH concentrations, indicators of chronic and peracute stress, respectively (Tripp et al, 2010).…”

“…A peracute stress response in wild manatees as a result of the capture and handling process has been documented by assaying for adrenocorticotropic hormone (ACTH) concentrations in plasma (Tripp et al, 2010). While capture-related deaths are rare, field biologists encounter animals during research captures and rescues with signs of bradycardia, apnea, hyperthermia, and hypothermia when compared to healthy resting individuals in a captive setting (Scholander & Irving, 1941;Gallivan et al, 1983;Irvine, 1983;Bossart, 2001;Murphy, 2003).…”

The physiological and behavioral responses of steers to gaseous ammonia in simulated long-distance transport by ship

“…The blood smears were stored at 4°C. The samples were used to determine plasma cortisol using an automated chemiluminescent EIA (Immulite 1000 Cortisol kits, sensitivity 0.2 μg/dL detected on an Immulite 1000 Analyser, Siemens Medical Solutions Diagnostics, Gwynedd, UK; assay validated by Tripp et al, 2010), blood urea using a kinetic UV test (OSR6134, ±0.35 at 7.75 mmol/L, Olympus AU400 Analyser, Life and Materials Science Europa GmBH, Hamburg, Germany), and a full blood count.…”

Influence of Collection and Storage Conditions on Adrenocorticotropic Hormone (ACTH) Measurements in Bottlenose Dolphins (Tursiops truncatus)

“…Therefore, ACTH is expected to be preferred to cortisol as an indicator of peracute stress when sample collections occur immediately following exposure to the stress event. This has been confirmed in the Florida manatee (Tripp et al, 2010). Further, studies in marine mammals have shown that ACTH elicits a greater magnitude of the mineralocorticoid aldosterone than it does in terrestrial mammals (St. Aubin & Dierauf, 2001).…”

“…Adrenocorticotropic Hormone (ACTH) and related hormones have been assessed in managed-care and free-ranging bottlenose dolphins (Tursiops truncatus) and other marine mammals as measurements of the stress response (Ortiz & Worthy, 2000;Forney et al, 2002;Schmitt et al, 2010;Tripp et al, 2010;Houser et al, 2011). The role ACTH plays in the adrenal mediated response in bottlenose dolphins is similar to that in other mammals (St. Aubin & Dierauf, 2001).…”