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Sonographic evaluation of thyroid morphology during different reproductive events in female Indo‐Pacific bottlenose dolphins, Tursiops aduncus
Author(s) -
Kot Brian C. W.,
Ying Michael T. C.,
Brook Fiona M.,
Kinoshita Reimi E.,
Kane David,
Chan Winson K.
Publication year - 2012
Publication title -
marine mammal science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.723
H-Index - 78
eISSN - 1748-7692
pISSN - 0824-0469
DOI - 10.1111/j.1748-7692.2011.00530.x
Subject(s) - thyroid , bottlenose dolphin , estrous cycle , biology , reproduction , lactation , physiology , female reproductive system , hormone , pregnancy , endocrinology , ecology , genetics
Thyroid morphology and function are likely affected by the cyclic hormonal environment during different reproductive events in females. The present study was undertaken to evaluate the variation of thyroid morphology at different reproductive events (anestrus, estrus, lactation, and pregnancy) in a captive group of Indo‐Pacific bottlenose dolphins ( Tursiops aduncus ) measured using sonography. Sonographic examinations of the thyroid gland and ovaries in nine sexually mature female subjects were performed weekly for 2.5 yr. A generalized linear mixed model was used to estimate the effects of the reproductive events for thyroid volume. Reproductive event was found to be a significant predictor for thyroid volume measurement and significant variation in thyroid volume was found between different reproductive events. A significantly larger thyroid volume in lactating females was observed when compared with estrous and anestrous females, possibly due to the high energy requirements and milk production during lactation. Taken together, thyroid volume variation during different reproductive events in female dolphins should be considered so as to obtain a diagnostically meaningful assessment when conducting routine examinations.