Abstract
Ingestion of foreign objects by cetaceans is a relatively common occurrence in captive animal facilities, especially closed systems, but occasionally in open ocean pen settings. The reason for the difference is the uniqueness of finding foreign objects in closed systems, where most of the ones that enter the pool are those provided as environmental enrichment by trainers or objects that either fall or are thrown into the pool by the guests. In open ocean pens, the vast majority of foreign objects are leaves, rocks, palm fronds, and algae balls.
Regardless of the source, a routine ultrasound examination should include an assessment of the fore and fundic stomach chambers of all dolphins.1 This should only be conducted on a fasted patient where the fundic stomach chamber is identified and the distance to the apex of the forestomach is measured. The distance can be mapped on the body surface and measured with a ruler, or by positioning the transducer longitudinally where the fundic stomach is identified on the left, the apex of the forestomach is on the right, and then the distance is measured on the machine.
The fasted forestomach may contain small amounts of water;2 however, in most instances gastric rugae can be identified. In the non-fasted stomach, it may be difficult to distinguish fish (especially after digestion) and ingested water from many of these foreign objects. In 32 dolphins ranging from 150–220 kg the normal longitudinal distance averaged 9–13 cm, nearly the longitudinal limit of the C60 Sonosite transducer (5–2 MHz). In contrast, this distance was as great as 26 cm in individuals containing foreign objects, obscuring rugae and luminal contents.
In our experience, individuals with 2–3 consecutive days of longitudinal distances greater than 20 cm were induced to vomit with 500 ml peroxide, consequently vomiting within 18–20 minutes. This procedure has been performed approximately 10 times and only two dolphins became inappetent immediately following vomition, but fully recovered the next day. To counteract this, 0.02 mg/kg dexamethasone was administered orally the night before the procedure and recovery was uneventful.
* Presenting author
References
1. Levine G, Selberg K, Sweeney J, Stone, R, Campbell M, Yanovitch C, Schif D. Gastric foreign bodies in small odontocetes: a clinical approach. In: Proceedings from the 45th Annual IAAAM Conference; May 17–22, 2014, Gold Coast Australia.
2. Brook FM, Van Bonn W, Jensen E. Ultrasonography. In: Dierauf LA, Gulland FMD, eds. CRC Handbook of Marine Mammal Medicine. 2nd ed. Boca Raton, FL: CRC Press LLC; 2001: 590–620.