A 14.6-yr-old, female, multiparous polar bear (Ursus maritimus) acutely developed an apparent hind limb weakness. Physical examination and diagnostic tests including a hemogram, serum biochemistry, electrolytes, radiographs, and myelogram did not provide a definitive diagnosis. No improvement in condition was noted during 4 days of supportive care, and the bear was euthanized. An ovoid mass was present in the anterior mediastinum, and a thymoma was confirmed histologically. Compared with control polar bears, elevated serum acetylcholine receptor (AChR) antibodies (0.13 ± 0.06 nmol/L vs. 0.86 nmol/L) were detected by immunoprecipitation radioimmunoassay, which is consistent with myasthenia gravis (MG) in other species. Although the AChR antibody test has not been validated in the polar bear, we are confident in the postmortem diagnosis of MG, which is commonly associated with thymoma in other species.
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1 September 2004
MYASTHENIA GRAVIS IN A POLAR BEAR (URSUS MARITIMUS)
David E. Kenny,
Jeffery Baier,
Felicia Knightly,
Daniel Steinheimer,
David M. Getzy,
G. Diane Shelton
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Journal of Zoo and Wildlife Medicine
Vol. 35 • No. 3
September 2004
Vol. 35 • No. 3
September 2004
AChR
myasthenia gravis
nicotinic acetylcholine receptors
polar bear
thymoma
Ursus maritimus