Prediction from ultrasonographic measurements of the expected delivery date in two species of bottlenosed dolphin (Tursiops truncatus and Tursiops aduncus )

Abstract

Ultrasonographic measurements were made at least once a month during 14 gestations in seven Tursiops truncatus and 12 gestations in five Tursiops aduncus (bottlenosed dolphins). The 121 measurements of the fetal biparietal diameter and 139 measurements of the fetal thoracic diameter in T truncatus and the 97 measurements of the biparietal diameter and 97 measurements of the thoracic diameter in Taduncus were used to establish regression lines for the increases in the diameter of the head and thorax of the fetus with time. From these relationships an easy-to-use computer program was developed to predict the date of birth of the two species of bottlenosed dolphin, and its predictions were compared with the actual dates of birth of other calves of both species. The births occurred within the range of predicted dates, and even when only a few measurements were available, the program provided accurate predictions.

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

“…In humans, increase in thyroid volume during pregnancy could be caused either by the demands of the growing fetus or by the hyperemia of the thyroid gland caused by the increased blood volume of the mother (Brander and Kivisaari 1989, Berghout and Wiersinga 1998, Glinoer 2005). In dolphins, Lacave et al (2004) proposed to divide the gestational period into three phases of 4 mo each. However, the lack of statistical significant difference in thyroid volume between anestrus and pregnancy in the present study is possibly due to the absence of an observable “trimester‐like” gestational period in dolphins.…”

“…Lactating was defined as the period which immediately follows a gestational period of a subject, lasting for up to 2 yr or more in captivity (Robeck et al 2001). Pregnancy was defined as the state in which the subject is fertilized and nurtures the fetus up until the point of delivery, lasting approximately 12 mo (Lacave et al 2004). Estrus was defined as the period in which a female is sexually receptive to males for the purposes of conception, lasting from 27 to 33 d (Brook 1997).…”

Low reproductive success rates of common bottlenose dolphins Tursiops truncatus in the northern Gulf of Mexico following the Deepwater Horizon disaster (2010-2015)

“…Pregnancies were classified as (1) confirmed pregnant: a fetus was detected; (2) probable pregnancy: a corpus luteum (CL) with or without uterine fluid was present in conjunction with a serum progesterone value greater than 5 ng ml −1 ; or (3) confirmed not pregnant: the ovary was seen without a CL, progesterone measurements were less than 5 ng ml −1 and the uterus was visualized without an embryo or fetus (Lane et al 2015). 'Confirmed pregnancies' were given estimated due dates based on fetal biparietal skull diameter (Stone et al 1999, Lacave et al 2004, Smith et al 2013. One sample classified as a 'probable pregnancy' was excluded from the statistical analyses given the unknown level of statistical uncertainty associated with this pregnancy classification (i.e.…”

Cetacea (Whales, Dolphins, Porpoises)

“…23 Thorough fetal echocardiography is possible, 57 particularly around months 8 to 9 of gestation. Fetal growth algorithms to predict the parturition date have been determined for bottlenose dolphins.…”