Abstract

The spiny softshell turtle is a threatened species in Canada.^1,2 A recovery plan, which included the implementation of a head-start program, was developed for the only known population of this species in the province of Québec.³ The purpose of the program is to increase juvenile survival over the first winter. Freshly laid eggs were collected and incubated and juvenile turtles were released at 10 months of age.³

High mortality rates were observed during the two first years of the head-start program [2014: 22.5% (7/31) and 2015: 55.0% (22/40)]. A significant proportion of the mortalities appeared to be associated with digestive tract perforations and resulting coelomitis. Cases were reviewed with the objective to better describe this clinical presentation and to provide insight into the possible underlying causes. Most of these animals were simply found dead, while others presented with lethargy, anasarca, and anorexia. Despite transient, general improvement in cases treated empirically with antibiotics and/or diuretics, mortality was the eventual outcome in all treated animals. In the examined turtles of both cohorts, coelomitis was the only established cause of mortality and was documented at an unusually high frequency (15/23). A digestive tract perforation was the underlying cause of coelomitis in most (11/15) of those individuals, with stomach and duodenum being the only affected segments. Despite the failure to identify a genuine perforation, a breach in the wall of the digestive tract was also considered to be the cause of coelomitis in the other cases (4/15) based on similar case presentations and necropsy findings. Microscopically, the coelomitis consisted of serosal mesothelial cell hypertrophy, fibrinous to granulomatous inflammation, visceral adhesions, as well as the presence of bacterial colonies. Alimentary particles associated with these lesions were observed in all cases with a confirmed perforation. Marked dilatation of the gastrointestinal tract, associated with abundant food material and suggestive of a digestive impaction/ileus, was repeatedly observed.

Digestive tract impactions were considered to have caused the perforations and the secondary coelomitis. General husbandry parameters (such as a suboptimal temperature)that could have potentially affected gastrointestinal transit were deemed appropriate for the species.⁴ We hypothesize that both an increase in the quantity of food offered and the substitution of freeze-dried Gammarus shrimp for larger and more abrasive sun-dried red shrimps (Solenocera melantho) could have been the principal factors responsible for the increased mortality rate during the second year of the program.⁵ The presence of coelomitis and perforations in 2014 suggests that some issues were present in the initial diet regimen as well.

Our observations suggest that gastrointestinal impactions may be associated with the ingestion of excessive amounts of food in juvenile spiny softshell turtles. Intraluminal pressure and the abrasive nature of food material, such as dried invertebrates, may have contributed to the ulceration and the eventual perforation at the pyloro-duodenal junction, leading to an ultimately fatal bacterial coelomitis. The impact of this syndrome in spiny softshell turtle conservation programs should be limited by preventive measures. Prospective dietary studies are warranted to establish optimal diet parameters in juvenile individuals from this species.

Acknowledgements

The authors wish to thank the veterinary technicians of the Zoo de Granby and the Centre québécois sur la santé des animaux sauvages, Drs. Rozenn Le Net and Christopher Scala for their contribution to post-mortem examinations, Amandine Vargas and Dr. Cédric B. Larouche for their guidance and contribution in processing the microscopic lesion figures and Samuel Mercier for his insight in the food processing industry.

* Presenting author
+ Student presenter

Literature Cited

1.  COSEWIC. 2002. COSEWIC assessment and update status report on the spiny softshell turtle Apalone spinifera in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa, Canada. vii + 17 pp.

2.  Species at Risk Act. 2015. Minister of Justice. Ottawa, Canada. 108 pp. Available at: http://laws-lois.justice.gc.ca. Accessed on October 11, 2016.

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5.  Kim H-K, Chang Y-S, Shin H-S. 1989. Effects of cooking and drying methods on the taste component and microstructure of shrimp. J Korean Agr Chem Soc. 32:278–285.