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Evaluation of Single-Sample Analysis of Progesterone in Combination with Relaxin for Diagnosis of Pregnancy in Wild Bottlenose Dolphins (Tursiops truncatus)

Author(s): Bergfelt, D.R.; B.G. Steinetz; J.S. Reif; A.M. Schaefer; G.D. Bossart; M.S. Mazzoil; E. Zolman; P.A. Fair


Publication Type: Journal Article

Journal Title: Aquatic Mammals

Date of Publication: 2013

Reference Information: 39(2): 198-206

Keywords: progesterone; relaxin; pregnancy; wild bottlenose dolphins; Tursiops truncatus

Abstract: The present study is a preliminary evaluation of the potential for an elevation in relaxin to clarify an elevation of progesterone in wild bottlenose dolphins as pregnancy-related, since relatively high progesterone in a single-sample analysis is not necessarily pregnancy-specific. Blood samples were collected from adult female dolphins in estuaries of Charleston, SC and the Indian River Lagoon, FL. Serum progesterone and relaxin concentrations were analyzed in the same samples (n=74) with respective RIAs. Diagnosis of pregnancy was based on concentrations of progesterone and relaxin >6.0 and >11.2 ng/mL, respectively, whereas non-pregnancy was based on respective hormone concentrations less than or equal to baseline concentrations. Progesterone was observed at elevated concentrations considered diagnostic of pregnancy in 20 and relaxin in 12 dolphins. In a contingency table analysis with progesterone as the conventional standard for pregnancy diagnosis, there was a 60% positive correspondence with relaxin (12 relaxin- out of 20 progesterone-diagnosed pregnancies) and 40% negative correspondence (8 relaxin-diagnosed non-pregnancies out of 20 progesterone-diagnosed pregnancies). Kappa analysis indicated good agreement (? = 74%) between relaxin- and progesterone-diagnosed pregnancies. Contingency table results were verified based on known pregnancies of 9 cow-calf pairs observed through photo-identification subsequent to health assessments. Concordance between hormone diagnosed and observed pregnancies was 9 of 9 (100%) for progesterone and 7 of 9 (78%) for relaxin. In conclusion, preliminary results indicated that relaxin may have limited value in pregnancy diagnosis when used alone. However, in combination with an elevation of progesterone in a single-sample analysis, a pregnancy-specific elevation of relaxin can clarify that progesterone is pregnancy-related and, thus, confirm the diagnosis of pregnancy in wild dolphins.