Ultrasound Evaluation of Ovaries and Uterus in Black Howler Monkeys (Alouatta caraya)

Background Ultrasound is a key diagnostic tool for evaluating reproductive anatomy and monitoring reproductive health in nonhuman primates. This study describes the reproductive system of female Alouatta caraya using ultrasonography. Methods Eleven females underwent transabdominal ultrasound using a 3–13 MHz linear array probe in B‐mode. Uterine volume ( UV ) and left and right ovarian volumes ( LtOV and RtOV ) were measured and correlated with age. Results The uterus and ovaries exhibited normal morphology, echotexture, and echogenicity. Follicles and/or corpus luteum were observed in all adults ( n = 3) and in 50% of juveniles ( n = 3/6). No difference was found between LtOV and RtOV , so their mean was used for analysis. UV and ovarian volume showed a positive correlation with age. Conclusion Age is a strong predictor of reproductive organ volume. These findings support reproductive monitoring and assisted reproduction in A. caraya .