INVESTIGATION OF THE USE OF SERUM BIOMARKERS FOR THE DETECTION OF CARDIAC DISEASE IN MARINE MAMMALS.

Cardiac disease has been extensively documented in marine mammals; however, it remains difficult to diagnose antemortem. Assays measuring cardiac troponin I (cTnI) and N-terminal pro-brain natriuretic peptide (NT-proBNP) are used as sensitive and specific biomarkers of cardiac disease in many species, but have not been widely investigated in marine mammals. This study aimed to provide a set of reference values for cTnI and NT-proBNP in belugas (BW) (Delphinapterus leucas), sea otters (SO) (Enhydra lutris), Steller sea lions (SSL) (Eumetopias jubatus), and California sea lions (CSL) (Zalophus californianus) with and without cardiac disease, and to determine if these biomarkers are useful indicators of cardiac disease in these species. First, existing immunoassays for cTnI and NT-proBNP were successfully validated utilizing species-specific heart lysate spiked serum. Cohorts were defined by histopathology as animals with no evidence of cardiac disease ("control"), with confirmed cardiac disease ("disease"), and with concurrent renal and cardiac disease ("renal") for which serum samples were then analyzed. Serum concentration ranges for cTnI (ng/ml) and NT-proBNP (pmol/L) were determined for control and disease cohorts. There was significantly higher cTnI (P= 0.003) and NT-proBNP (P= 0.004) concentrations in the CSL disease cohort, as well as positive trends in BW, SO, and SSL disease cohorts that did not reach statistical significance. NT-proBNP concentrations were significantly higher in the CSL renal cohort compared with the control (P < 0.001) and disease (P= 0.007) cohorts. These results suggest that cTnI and NT-proBNP may be clinically useful in the antemortem diagnosis of cardiac disease in CSL, and warrant further investigation in BW, SO, and SL.

RADIOGRAPHIC DETERMINATION OF GASTRIC EMPTYING AND GASTROINTESTINAL TRANSIT TIME IN COWNOSE RAYS (RHINOPTERA BONASUS) AND WHITESPOTTED BAMBOO SHARKS (CHILOSCYLLIUM PLAGIOSUM) AND THE EFFECT OF METOCLOPRAMIDE ON GASTROINTESTINAL MOTILITY.

Gastrointestinal (GI) pathology is common in elasmobranchs; however, information regarding normal GI transit time and the effect of therapeutics on GI motility is lacking. The objective of this study was to determine baseline gastric emptying and GI transit times in cownose rays (Rhinoptera bonasus) and whitespotted bamboo sharks (Chiloscyllium plagiosum) via radiographic barium sulfate contrast studies. Additionally, a pilot study was undertaken to determine the effect of metoclopramide on GI transit time in whitespotted bamboo sharks. Eight cownose rays and eight whitespotted bamboo sharks were administered a 98% w/w barium sulfate suspension at 8 ml/kg via orogastric tube. Post-contrast radiographs were obtained at 2 min, 3, 6, 12, and 23 hr for rays; and 2 min, 3, 6, 9, 12, 16, 25, 30, 36, and every 12 hr until complete gastric emptying occurred for sharks. In cownose rays, the mean and standard error were established for time of initial spiral colon filling (3.4 ± 0.4 hr), complete spiral colon opacification (12 ± 0 hr), initial spiral colon emptying (21.6 ± 1.4 hr), and complete gastric emptying (23 ± 0 hr). In bamboo sharks, the mean and standard error were established for time of initial spiral colon filling (5.3 ± 0.5 hr), complete spiral colon opacification (12.4 ± 1.3 hr), initial spiral colon emptying (22.5 ± 2.7 hr), and complete gastric emptying (39.9 ± 3.3 hr). Cownose rays had a significantly shorter time to spiral colon filling and complete gastric emptying compared with bamboo sharks (P < 0.05). Whitespotted bamboo sharks (n = 8) were administered metoclopramide (0.4 mg/kg orally once daily for 10 days) and the barium series was repeated. Complete gastric emptying time was significantly shorter in treated sharks compared with control (P < 0.05), suggesting that metoclopramide may be a useful therapeutic for GI motility disorders in elasmobranchs.