Accuracy of assessment of luteal morphology and luteal blood flow for prediction of early pregnancy in goats

This study aims to determine the best post-breeding time for an early pregnancy diagnosis in dairy goats, when using luteal morphology and vascularization assessment by B-Mode and color Doppler ultrasonography (US) in association or not with the anechoic uterine content. A total of 131 Saanen goats (2.0 ± 0.5 years old) were used in the two studies. In the first study, pregnancy prediction was daily performed from Day 15–23 post-breeding in 51 does. This was based on a subjective assessment of luteal morphology (B-Mode US), luteal blood flow (color Doppler US), and the presence of anechoic uterine content (B-Mode US). In the second study, pregnancy predictions were performed in 71 does on the best post-breeding day, as determined in the first study (Day 21 using luteal blood-flow assessment and Day 23 using luteal morphological assessment and overall analysis). In both studies, pregnancy diagnosis was confirmed on Day 30 (gold standard method by B-Mode transrectal ultrasonography). The B-Mode and color Doppler US performance in reaching an early pregnancy diagnosis was evaluated by calculating sensitivity (Sens), specificity (Spec), negative and positive predictive values (NPV and PPV), accuracy (Acc), the Kappa index (κ), and the Younden index (J). In Study 1, the pregnancy prediction accuracy progressively increased from Day 17–23 using B-Mode US (D17: 50.98%; D18: 52.94%; D19: 62.75%; D20: 74.51%; D21: 86.27%; D22: 90.20%; D23: 96.08%), and from Day 17–21 using color Doppler US (D17: 49.02%; D18: 54.90%; D19: 70.59%; D20: 86.27%; D21: 96.08%). In the second study, color Doppler, B-Mode, and overall assessments at Day 21 and Day 23, respectively, presented a similar pattern of sensitivity, specificity, and accuracy as was found in the first study. Therefore, both color Doppler and B-Mode assessments can be judged as effective tools for reaching a pregnancy diagnosis in goats as early as on Day 21 and Day 23, respectively, post-breeding. •Luteal blood-flow evaluation enables early pregnancy diagnosis on Day 21.•Luteal morphological evaluation enables early pregnancy diagnosis on Day 23.•Uterine content assessment should be carried out with luteal evaluation to get high accuracy.•Luteal and uterine assessments are important for dairy goat resynchronization programs.