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Gen Comp Endocrinol. 2014 Feb 1;197:73-81. doi: 10.1016/j.ygcen.2013.11.021. Epub 2013 Dec 7.

Thyroid hormone concentrations in relation to age, sex, pregnancy, and perinatal loss in bottlenose dolphins (Tursiops truncatus).

Author information

1
Hawaii Pacific University, College of Natural and Computational Sciences, Kaneohe, HI 96744, United States. Electronic address: kwest@hpu.edu.
2
Indianapolis Zoo, 1200 W. Washington St., PO Box 22309, Indianapolis, IN 46222, United States. Electronic address: jramer@indyzoo.com.
3
Department of Reproductive Sciences, Conservation and Research Center, National Zoological Park, Smithsonian Institution, Front Royal, VA 22630, United States. Electronic address: brownjan@si.edu.
4
Quest Global Management/Dolphin Quest, 4467 Saratoga Ave., San Diego, CA 92107, United States. Electronic address: jsweeney@dolphinquest.com.
5
Dolphin Quest Hawaii, Waikoloa Beach Drive, Waikoloa, HI 96738, United States. Electronic address: ehanahoe@hotmail.com.
6
Sea World of California, San Diego, CA 92109, United States. Electronic address: reidarsongroup@me.com.
7
Indianapolis Zoo, 1200 W. Washington St., PO Box 22309, Indianapolis, IN 46222, United States. Electronic address: jproudfoot@indyzoo.com.
8
US Environmental Protection Agency, Washington, DC 20460, United States. Electronic address: Bergfelt.Don@epa.gov.

Abstract

This study evaluated circulating concentrations of thyroid hormones in relation to age, sex, pregnancy status, and perinatal loss in bottlenose dolphins (Tursiops truncatus) under human care. A total of 373 blood samples were collected from 60 individual dolphins housed at nine aquariums/oceanariums. Serum concentrations of total and free thyroxine (T4) and triiodothyronine (T3) were analyzed with commercial RIA kits validated for use with dolphins. While the effect of age was indicated by higher (P<0.0001) concentrations of total and free T4 and T3 in juveniles than adults, the effect of sex on thyroid hormones was inconclusive. The effect of pregnancy was indicated by higher (P<0.035) total and free T4 and T3 during early pregnancy compared to non-pregnancy. For both successful and unsuccessful pregnancy outcomes, maternal concentrations of thyroid hormones were highest during early, intermediate during mid, and lowest during late pregnancy (P<0.07 to P<0.0001). Compared to live and thriving births, concentrations of total and free T4 and total T3 were lower (P<0.08 to P<0.001) in dolphins with perinatal loss. Lower concentrations ranged from 10% to 14% during early, 11% to 18% during mid, and 23% to 37% during late pregnancy. In conclusion, the effects of age, reproductive status and stage of pregnancy on thyroid hormone concentrations are necessary factors to take into account when assessing thyroid gland function. Since perinatal loss may be associated with hypothyroidism in dolphins, analysis of serum T4 and T3 should be considered for those dolphins that have a history of pregnancy loss.

KEYWORDS:

Age; Bottlenose dolphin; Perinatal loss; Pregnancy; Sex; Thyroid hormones

PMID:
24321177
DOI:
10.1016/j.ygcen.2013.11.021
[Indexed for MEDLINE]
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