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14)
Immunology
I know of no publications on the immunology of walruses.
15)
Pathological features
Various surveys for antibodies have been conducted in walruses and other
pinnipeds. Calle et al. (2002) found no antibodies against Brucella
sp. in the Pacific walrus, 3 of 40 had antibodies against Leptospira
interrogans, but phocine distemper was not detected. A variety of
other antibodies existed (against calicivirus, vesicular exanthema, and
various subtypes of influenza A). Nielsen et al. (2000) detected antibodies
against morbillivirus in 50 of Atlantic walruses and, in 2001, identified
antibodies to Brucella but they were unable to identify the organism.
Although Zarnke et al. (1997) identified antibodies to phocid herpesviruses,
they were of the opinion that herpes infection was not a cause of mortality.
Antibodies against caliciviruses were detected in Pacific walruses by
Barlough et al. (1986) who had also earlier identified the virus.
Trichinella infection is common in walrus and it is a source of infection
to the Inuits (Proulx et al., 2002). Brucellosis of sea mammals was studied
by Foster et al. (2002) who separated the responsible organism of terrestrial
animals from those in sea mammals (Brucella cetaceae & B.
pinnipedia). A listing of parasites found in walruses was provided
by Dailey & Brownell (1972).
Myocardial infarction and widespread atherosclerosis was the cause of
death in a 25 year-old walrus reported by Gruber et al. (2002).
Cornell et al. (1975) described an unusual complication of neonatal life,
the persistence of a tight fibrous band expanding from the dome of the
bladder to the umbilicus that prevented complete emptying of the bladder.
The about one month-old, 69 kg walrus had been hand-reared and developed
pyelonephritis and hydronephrosis from this complication and died. It
also had ascites and intestinal torsion.
16)
Physiologic data
No physiological studies on placenta or uterine perfusion have been undertaken
on walrus implantations. There is, however, an excellent consideration
of the development of the (probably similar) endotheliochorial placentation
in mink (Pfarrer et al., 1999). It described the development of the maternal
sinusoids from endometrial capillaries through the invasive action of
the syncytiotrophoblast in three developmental stages. Histologic studies
and corrosion casts were employed and these authors provided an excellent
overview of the features of placental perfusion in endotheliochorial placentas.
17)
Other resources
To the best of my knowledge, the only cell lines available are those of
Dr. U. Anderson at the University of Lund, Sweden.
18)
Other remarks - What additional Information is needed?
No implantational study has been undertaken and the length of the umbilical
cord needs to be ascertained. Endocrine studies are completely lacking.
Acknowledgement
The animal photograph in this chapter was kindly supplied by Dr. Sam Ridgway.
I very much appreciate the help of Dr. Judy St. Leger of Sea World, San
Diego for allowing me to study this placenta. Dr. Carlos Rodriguez, New York Wildlife Conservation Society kindly made the second placenta available. I also wish to acknowledge
the constant help of the histopathologists at UCSD Medical Center in preparing
the slides.
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