Abstract

Neonatal harbor seals (Phoca vitulina) are one of the most common marine mammal species in rehabilitation facilities world-wide, with hundreds of individuals a year receiving intensive nutritional support and clinical care. Post mortem examination of pups that die has revealed that the ductus arteriosus and foramen ovale are often patent in pups under one month of age.¹ The clinical significance of these patent embryonic structures is unclear, as previous surveys of lesions in seals have reported patent ductus arteriosus as a congenital defect,² yet they are commonly observed in animals dying from unrelated causes. It is thus possible that the timing of closure of these structures in diving mammals differs from that in terrestrial species.

Here we describe the use of real time two dimensional echocardiography (with color Doppler) to characterize changes in cardiac hemodynamics in neonatal seals with age, and the clinical significance of these changes. Ten neonatal harbor seals were examined daily from admission to The Marine Mammal Center at < 24 hours old (determined by observation of birth, presence of a moist pink umbilicus and lanugo coat, absence of teeth) to the day after closure of the ductus arteriosus was observed. Results indicate the foramen ovale can remain patent for up to 2 weeks post partum, and the ductus arteriosus may remain patent for up to 3 weeks of age.

Acknowledgements

We thank the staff and volunteers of The Marine Mammal Center for their hard work in caring for these animals.

References

1.  Trupkiewicz J, Gulland FMD, Lowenstine LJ 1997. Congenital defects in northern elephant seals stranded along the central California coast. Journal of Wildlife Diseases 33:220-225.

2.  Banish LB, Gilmartin WG 1992. Pathological findings in the Hawaiian monk seal. Journal of Wildlife Diseases 28:428-434.