Conjoined Fetal Twins in a Harbor Seal (<i>Phoca vitulina</i>)

Olson, Jennifer K.; Gaydos, Joseph K.; McKlveen, Tori L.; Poppenga, Robert H.; Wicinas, Kay; Anderson, Erik; Raverty, Stephen

doi:10.7589/2015-02-045

Cited by 4 publications

(5 citation statements)

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“…The elevated levels of these trace minerals may be attributed to enzymatic deficiencies or in utero exposure and assimilation and did not appear to affect normal fetal development directly. The previously described case of conjoined twins had detectable hepatic levels of phenol, indole, and hydrocinnamic acid (Olson et al 2016).…”

mentioning

confidence: 71%

“…3). Cleft lip was noted in one of the previously described conjoined twins (2013-SJ013; Olson et al 2016). One case (WDFW2016-075) presented with dwarfism, cataracts, and abnormally long non-lanugo fur.…”

mentioning

confidence: 89%

“…Congenital diseases (structural or functional developmental abnormalities present at birth) have been previously identified in harbor seals (Phoca vitulina). They include odontogenic (Suzuki et al 1990), cephalic, and occipital bone malformations (Dennison et al 2009); cleft palate (Suzuki et al 1992); conjoined twins (Olson et al 2016); fetus in fetu (Buckles et al 2006); ectrodactyly (Tarasoff and Pié rard 1970); dwarfism (Newby 1971); hemicerebral anomaly (McKnight et al 2005); intestinal atresia (St. Leger and Nilson 2014); and neuroglial heterotopia (Harris et al 2011). Congenital deformities in animals can be associated with infectious diseases (Konno et al 1982), maternal exposure to toxins (Harris et al 2011), or genetic defects (Mansfield and Land 2002), or they can be idiopathic and related to disordered embryonic migration and fusion (Olson et al 2016).…”

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confidence: 99%

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Congenital Diseases in Harbor Seals (Phoca vitulina richardsii) from the Salish Sea

D’Agnese¹,

Lambourn

Olson

et al. 2021

Journal of Wildlife Diseases

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confidence: 71%

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confidence: 89%

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confidence: 99%

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Congenital Diseases in Harbor Seals (Phoca vitulina richardsii) from the Salish Sea

D’Agnese¹,

Lambourn

Olson

et al. 2021

Journal of Wildlife Diseases

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“…In a survey from 1671 to 2006, only 19 records, to which two more could have been added (Peterson and Fenton, ; Canfield et al., ), were found by Kompanje and Hermans (). The list of mammalian orders with available records includes nowadays Primates, Rodentia, Lagomorpha, Erinaceomorpha, Chiroptera, Carnivora and Cetartiodactyla (Kompanje and Hermans, ; Langer et al., ; Urban et al., ; Olson et al., ).…”

Section: Introductionmentioning

confidence: 99%

Dicephalic Parapagus Conjoined Twins in a Large Fruit‐eating Bat, Genus Artibeus (Chiroptera, Phyllostomidae)

Nogueira

Ventura

Veiga

et al. 2017

Anat Histol Embryol

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Conjoined twinning is an embryological anomaly rarely reported in wild mammals and with only two previous records in Chiroptera. Here, we report a case of dicephalic parapagus conjoined twins in the Neotropical phyllostomid genus Artibeus. These twins are males and present separated heads and necks, but a conjoined trunk with an expanded upper thoracic region. They developed two complete forelimbs and two complete hindlimbs, all laterally to the trunk. There is a volume in the upper midback and between the heads that resembles a third rudimentary medial forelimb, but X-ray images only suggest the presence of medial skeletal elements of the pectoral girdle (clavicle and scapulae) in this region. The X-ray images also show that vertebral columns run separated from head until the base of lumbar region, where they form a single structure. Using ultrasound images, we detected the presence of two similarly sized and apparently separated hearts. The accumulation of study cases like this will help in the understanding of patterns and process behind this phenomena, and collection material plays a key role in this context.

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“…After the first parturition, females annually give birth to a single pup, weighing approximately 9 kg. In very rare occasions, twins may occur (Spotte 1982, Olson et al 2016). In the Netherlands, peak in pupping occurs in early June (Reijnders et al 2010b).…”

Section: Phenology Mirrored Annual Cyclesmentioning

confidence: 99%

Seals in motion : how movements drive population development of harbour seals and grey seals in the North Sea

Brasseur

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Terrestrial and marine wildlife populations have been severely reduced by hunting, fishing and habitat destruction, especially in the last centuries. Although management regulations have led to the recovery of some populations, the underlying processes are not always well understood. This study uses a 40-year time series of counts of harbour seals (Phoca vitulina) in the Wadden Sea to study these processes, and demonstrates the influence of historical regional differences in management regimes on the recovery of this population. While the Wadden Sea is considered one ecologically coupled zone, with a distinct harbour seal population, the area is divided into four geo-political regions i.e. the Netherlands, Lower Saxony including Hamburg, Schleswig-Holstein and Denmark. Gradually, seal hunting was banned between 1962 and 1977 in the different regions. Counts of moulting harbour seals and pup counts, obtained during aerial surveys between 1974 and 2014, show a population growth from approximately 4500 to 39,000 individuals. Population growth models were developed to assess if population growth differed between regions, taking into account two Phocine Distemper Virus (PDV) epizootics, in 1988 and 2002 which seriously affected the population. After a slow start prior to the first epizootic, the overall population grew exponentially at rates close to assumed maximum rates of increase in a harbour seal population. Recently, growth slowed down, potentially indicative of approaching carrying capacity. Regional differences in growth rates were demonstrated, with the highest recovery in Netherlands after the first PDV epizootic (i.e. 17.9%), suggesting that growth was fuelled by migration from the other regions, where growth remained at or below the intrinsic growth rate (13%). The seals' distribution changed, and although the proportion of seals counted in the German regions declined, they remained by far the most important pupping region, with approximately 70% of all pups being born there. It is hypothesised that differences in hunting regime, preceding the protection in the 1960's and 1970's, created unbalance in the distribution of breeding females throughout the Wadden Sea, which prevailed for decades. Breeding site fidelity promoted the growth in pup numbers at less affected breeding sites, while recolonisation of new breeding areas would be suppressed by the philopatry displayed by the animals born there. This study shows that for long-lived species, variable management regimes in this case hunting regulations, across a species' range can drive population dynamics for several generations.

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Conjoined Fetal Twins in a Harbor Seal (Phoca vitulina)

Abstract: In July 2013, a stranded harbor seal (Phoca vitulina) died giving birth to conjoined fetuses. The twins were joined at the abdomen and thoracolumbar spine with the vertebral axis at 180u. The cause of this unique anomaly-a first for this species-was not identified.

Cited by 4 publications

References 14 publications

Congenital Diseases in Harbor Seals (Phoca vitulina richardsii) from the Salish Sea

Congenital Diseases in Harbor Seals (Phoca vitulina richardsii) from the Salish Sea

Dicephalic Parapagus Conjoined Twins in a Large Fruit‐eating Bat, Genus Artibeus (Chiroptera, Phyllostomidae)

Seals in motion : how movements drive population development of harbour seals and grey seals in the North Sea

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