Abstract
In March 2006, a dead, juvenile, male bottlenose dolphin (Tursiops truncatus) was found in the marsh in Charleston, South Carolina. During necropsy, an enterolith was discovered completely obstructing the intestinal lumen. Further examination of the enterolith revealed a stingray spine nidus. The stingray spine was identified as belonging to the Southern stingray (Dasyatis americana). Interactions with stingrays are not uncommon for marine mammals2,7-8,16; however, linking the postmortem presence of stingray spines to the cause of death can be difficult. In this particular case, the state of decomposition hindered external and internal observations of spine penetration and migration. Enteroliths have been found in many terrestrial mammals and humans1,4,6,9,11,14,17, but they have apparently not been reported in bottlenose dolphins. Enterolithiasis has been linked to diet5-6, genetics4,6, alkaline intestinal environments3,10,13,15, and, as in this particular case, the ingestion and retention of foreign bodies.6,9,12,14 Most terrestrial enteroliths are composed primarily of struvite (magnesium ammonium phosphate)5-6,9,12,14; however, the composition of this enterolith from a bottlenose dolphin was primarily calcium phosphate carbonate. This case study emphasizes the need for thorough post-mortem examinations of carcasses, and provides an interesting comparison of the enterolith mineral composition between marine and terrestrial animals.
Acknowledgements
The authors would like to thank R. Sayre for assistance with the stranding response and necropsy of this bottlenose dolphin, F. Townsend for his veterinary expertise, W. McFee for his necropsy and sample analysis expertise, B. Roumillat Sr. for species identification of the stingray spine, and B. Roumillat Jr. for radiographs of the enterolith.
References
1. Crane PW, PR Crocker, DA Levison, OJA Gilmore. 1988. Enterolith ileus. Journal of the Royal Society of Medicine 81: 292-294.
2. Duignan PJ, JEB Hunter, IN Visser, G W. Jones, A Nutman. 2000. Stingray spines: A potential cause of killer whale mortality in New Zealand. Aquatic Mammals 26: 143-147.
3. Gamblin TC, J Glenn, D Herring, WB Mckinney. 2003. Bowel obstruction caused by a Meckel's diverticulum enterolith: A case report and review of the literature. Current Surgery 60: 63-64.
4. Hassel DM, JR Snyder, DM Langer, CM Drake, TB Yarbrough. 1997. Equine enterolithiasis: A review and retrospective analysis of 900 cases (1973-1996). Soft Tissue Surgery 43: 246-247.
5. Hassel DM. 2002. Enterolithiasis. Clinical Techniques in Equine Practice 1: 143-147.
6. Lloyd K, HF Hintz, JD Wheat, HF Schryver. 1987. Enteroliths in horses. The Cornell Veterinarian 77: 172-186.
7. Mcfee W, H Root, R Friedman, E Zolman. 1997. A stingray spine in the scapula of a bottlenose dolphin. Journal of Wildlife Diseases 33: 921-924.
8. Mclellan WA, VG Thayer, DA Pabst. 1996. Stingray spine mortality in a bottlenose dolphin, Tursiops truncatus, from North Carolina waters. The Journal of the Elisha Mitchell Scientific Society 112: 98-101.
9. Milton C, JM Axelrod. 1951. Calculi and other stones found in mammals. Journal of Mammology 32: 139-154.
10. Phelan M, H Kaufman, J Becker, G Fitzpatrick. 1997. Small bowel obstruction by jejunal enterolith. Surgery 121: 229-230.
11. Raper HS. 1921. A human enterolith containing choleic acid. Biochemical Journal 15: 49-52.
12. Schiffman, P. 1998. Mineralogical investigation of an enterolith from a Grant's Zebra. Environmental Geochemistry and Health 20: 103-112.
13. Spence LD, V Moran. 1995. Meckel's diverticulitis secondary to an enterolith. European Journal of Radiology 21: 92-93.
14. Taylor KS., G Faure. 1983. Geochemical study of an equine enterolith, Medina County, Ohio. Ohio Journal of Science 83: 54-59.
15. Tien YW, PH Lee, KJ Chang. 1999. Enterolith: An unusual cause of afferent loop obstruction. The American Journal of Gastroenterology 94: 1391-1392.
16. Walsh MT, D Beusse, GD Bossart, WG Young, DK Odell, GW Patton. 1988. Ray encounters as a mortality factor in Atlantic bottlenose dolphins (Tursiops truncatus). Marine Mammal Science 4: 154-162.
17. Yuki M, N Sugimoto, K Takahashi, H Ohtsuka, N Nishii, K Suzuki. 2006. Enterolithiasis in a cat. Journal of Feline Medicine and Surgery 8: 349-352.