Sonographic evaluation of thyroid morphology during different reproductive events in female Indo-Pacific bottlenose dolphins, Tursiops aduncus

Brian C W Kot, Tin Cheung Ying, Fiona M. Brook, Reimi E. Kinoshita, David Kane, Winson K. Chan

Research output: Journal article publicationJournal articleAcademic researchpeer-review

6 Citations (Scopus)


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.
Original languageEnglish
Pages (from-to)733-750
Number of pages18
JournalMarine Mammal Science
Issue number4
Publication statusPublished - 1 Oct 2012


  • Anestrus
  • Estrus
  • Indo-Pacific bottlenose dolphin
  • Lactation
  • Pregnancy
  • Thyroid gland
  • Tursiops aduncus

ASJC Scopus subject areas

  • Aquatic Science
  • Ecology, Evolution, Behavior and Systematics

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