Aquatic Mammals 2011, 37(2), 161-166, DOI 10.1578/AM.37.2.2011.161 Foramen Ovale and Ductus Arteriosus Patency in Neonatal Harbor Seal (Phoca vitulina) Pups in Rehabilitation Sophie E. Dennison, Marjorie Boor, Deborah Fauquier, William Van Bonn, Denise J. Greig, and Frances M. D. Gulland The Marine Mammal Center, 2000 Bunker Road, Sausalito, CA 94965, USA; E-mail (Dennison): vetradiologist@hotmail.com Abstract Twenty neonatal harbor seal (Phoca vitulina) pups in rehabilitation following maternal separa- tion underwent serial echocardiographic studies to assess patency and subsequent age of functional closure of the ductus arteriosus (d.a.). B-mode, color-flow Doppler, and pulse and continuous wave Doppler were utilized to identify the d.a. and determine patency and directionality of blood flow. Seals were also evaluated for evidence of foramen ovale (f.o.) patency. B-mode ultrasound was used to evaluate the inter-atrial septum for abnormal (aneurismal) motion, a sign of f.o. pat- ency in other species. In one harbor seal, this motion was confirmed as being consistent with f.o. patency by contrast echocardiography. Closure of the f.o. was not confirmed in any harbor seal prior to release back into the free-ranging population. Data acquired indicate that there is patency of the f.o. and d.a. after birth for a longer period in phocids than in described terrestrial mammals. The f.o. may be patent up to 7 wks of age, and the d.a. may be patent up to 6 wks of age without evidence of clinical consequence. This difference in ontogeny between terrestrial mammals and harbor seals is presumptively a diving adaptation. Such an adaptation is counterintuitive given that humans with f.o. patency are at increased risk of stroke following the introduction or formation of intravascular gas bubbles and suggests that con- current protective mechanisms may be present. Key Words: echocardiography, echocardiology, harbor seals, Phoca vitulina, pinniped, congenital defect Introduction Neonatal harbor seals (Phoca vitulina) are one of the most common marine mammal species in rehabilita- tion facilities worldwide, with hundreds of individu- als a year receiving intensive nutritional support and clinical care. Patent ductus arteriosis (d.a.) and patent foramen ovale (f.o.) have been noted during necropsies in harbor seal pups under 1 mo of age that were presumed premature due to the presence of a lanugo coat post partum (Dierauf et al., 1986). In those animals, patent d.a. has been reported as a congenital defect in some; while in others, the cause of death has been attributed to unrelated pathology and the patent d.a. considered incidental (Colegrove et al., 2005). Patent d.a. has also been reported as a cause of death in Hawaiian monk seals (Monachus schauinslandi) (Banish & Gilmartin, 1992). The clinical significance of patency of these structures in neonatal harbor seals is thus unclear. To determine whether such patency was ontogenically normal, this study aimed to demonstrate the presence of d.a. and f.o. patency and to determine the approximate age of functional closure of the d.a. in neonatal harbor seals in rehabilitation. Materials and Methods Twenty harbor seals were recruited for the study. All of the harbor seals were considered clinically healthy with the exception of varying degrees of malnutrition from maternal separation that resulted in their rescue from along the northern California coast. Six harbor seals had full lanugo coats at admission (five males and one female), nine had partial lanugo coats at admission (four male and five female), and five had no evidence of lanugo coats at admission (two males and three females) (Dierauf et al., 1986). All harbor seals with full or partial lanugo coats were admitted between 27 February and 27 March. All harbor seals with- out evidence of lanugo coats were admitted on 1 April or later. All harbor seals with lanugo coats at admission completely lost their lanugo coats at varying times during the study period. Harbor seals had an estimated age of between 0 to 1 d and 7 to 10 d at admission (Dierauf et al., 1986). Seventeen harbor seals were born prior to 15 April and were thus considered premature (Greig et al., 2010);