Cytologic examination is a common, inexpensive, and readily available diagnostic tool that serves as a valuable aspect of a medical evaluation for both terrestrial and aquatic species.4,5 In addition, basic laboratory tests such as hematology, serum biochemistry, and serum protein electrophoresis blood values are frequently utilized by veterinarians and resource managers to assess the health of wild stock.1,2 With the increasing rates of morbidity and mortality amongst wild cetacean species worldwide, broad-based medical and environmental examination has become paramount for conservation efforts.
As part of the multidisciplinary, multi-collaborative Bottlenose Dolphin Health and Environmental Risk Assessment study (HERA) initiated by the Harbor Branch Oceanographic Marine Mammal Research and Conservation Program in Ft. Pierce, FL and the National Ocean Services in Charleston, SC, blood and gastric fluid were collected from Atlantic bottlenose dolphins (Tursiops truncatus) to assess the presence and degree of gastric inflammation, as well as various blood parameters in the Indian River Lagoon, FL (IRL) dolphin population from 2003 to 2007. A total of 62 individual Atlantic bottlenose dolphin cytologic and blood samples were included in the analyses. Forestomach fluid bacterial and fungal cultures were available for 28 individual dolphins. Blood parameters evaluated included hematology, serum chemistry, serum protein electrophoresis, serum cortisol and serum aldosterone.
Nineteen (31%) of the 62 samples analyzed showed evidence of gastric inflammation, and 44 dolphins were identified as devoid of gastric inflammation and classified as clinically healthy based on parameters previously described.3 Of the 19 affected dolphins, 42.1% exhibited mild neutrophilic inflammation, 26.3% had moderate neutrophilic inflammation and 31.6% had severe neutrophilic inflammation. Serum chemistry analyses revealed that BUN/creatinine (54.9 ± 1.7) and iron (84.3 ± 21.4) were not significantly lower in dolphins with gastric inflammation than in those without the disorder. However, both values were lower and therefore clinically significant compared to previously established ranges for BUN/Creatinine (65 ± 19.2) and iron (98.8 ± 35.1) in healthy dolphins from the Indian River Lagoon FL.2 Acute phase protein alpha-2 globulin (0.8 ± 0.2) was significantly lower (p = 0.03) in dolphins exhibiting gastric inflammation compared to unaffected controls. There were no clinically significant aerobic/anaerobic or fungal culture results from dolphins with or without gastric inflammation. Bacteria cultured from both sample groups were considered to represent normal gastric flora. Antibiotic resistance patterns for affected and unaffected dolphins were examined but no significant differences were found. Additionally, the differences in mean serum cortisol and mean aldosterone values between dolphin cases and healthy controls were not statistically significant.
Results of this study confirm that hematologic analyses coupled with cytologic sampling provides a useful tool in diagnosing and surveying the prevalence of gastric disease in wild bottlenose dolphin populations. Gastric inflammation may constitute a marker of systemic illness in dolphins as supported by finding other abnormalities among affected animals.4 However, caution in interpreting findings should be used when examining populations at a single point in time, as opposed to serial investigations. The data obtained during the current study provide a baseline for further investigations and monitoring of both wild and captive bottlenose dolphin health.
This work was conducted under NMFS permit 998-1678 issued to Dr. Gregory Bossart as part of the Health and Risk Assessment of Bottlenose Dolphins Project (HERA) conducted in the Indian River Lagoon, FL and the Coastal waters of Charleston, SC.
1. Fair P.A., T.C. Hulsey, R.A. Varela, J.D. Goldstein, J. Adams, E.S. Zolman, and G.D. Bossart. 2006. Hematology, serum chemistry, and cytology findings from apparently healthy Atlantic bottlenose dolphins (Tursiops truncatus) inhabiting the estuarine waters of Charleston, South Carolina. Aquatic Mammals 32: 182-195.
2. Goldstein J.D., E. Reese, J.S. Reif, R.A. Varela, S.D. McCulloch, R.H. Defran, P.A. Fair, and G.D. Bossart. 2006. Hematologic, biochemical, and cytologic findings from apparently healthy Atlantic bottlenose dolphins (Tursiops truncatus) inhabiting the Indian River Lagoon, Florida. J Wildl Dis 42: 447-454.
3. Reif J.S., P.A. Fair, J.A. Adams, B.A. Joseph, D.S. Kilpatrick, J.D. Sanchez, J.D. Goldstein, F.I. Townsend, S.D. McCulloch, M. Mazzoil, E.S. Zolman, L.J. Hansen, and G.D. Bossart. 2008. Evaluation and comparison of the health status of Atlantic bottlenose dolphins from the Indian River Lagoon, Florida and Charleston, South Carolina. J Am Vet Med Assoc 233: 299-307.
4. Sweeney J.C., and M.L Reddy. 2001. Cetacean cytology. CRC Handbook of Marine Mammal Medicine, 2nd edition, Dierauf, L.A., and Gulland, M.D. (Eds.), CRC Press, Boca Raton, FL; Pp. 437-448.
5. Varela R.A., K. Schmidt, J.D. Goldstein, and G.D. Bossart. 2007. Evaluation of cetacean and sirenian cytologic samples. Vet Clin N Am Exot Anim Pract 10: 79-130.