Capuchin monkeys (Sapajus spp.) are South American ("New World") primates. They are commonly used for medical and behavioral research and are also targets of species rescue programs. Therefore, veterinary medical evaluation of these monkeys occurs commonly.Abdominal ultrasound is a widely used, inexpensive, safe, noninvasive method for anatomical evaluation of the abdominal organs.In Capuchin monkeys, previous studies of abdominal ultrasound determined the normal anatomy and physiology, but not all organs were evaluated. In one study, 1 abdominal ultrasonography was found useful in assessing anatomic morphology and physiology of the female reproductive tract. In another study, 2 investigators examined multiple abdominal organs of ten monkeys, but failed to provide all data.In a third study, 3 investigators examined ten monkeys only to standardize the gastric wall morphology (thickening and stratigraphy).Therefore, we sought to determine the normal ultrasonographic appearance and measurements of all the abdominal organs and structures of interest that can be routinely detected by ultrasound examination. | MATERIAL S AND ME THODSTwelve monkeys were enrolled (seven females and five males). The animals were housed at National Research Centre (CNR) where they are involved in behavioral studies. The animals, aging from 6 and 19 years and weighing from 1.18 to 3.78 kg, were considered healthy on the basis of history, Abstract Background: Previous ultrasonographic studies of Sapajus apella to determine the normal anatomy and physiology are incomplete. The aim of this study was to determine normal ultrasonographic appearance and measurements of all abdominal organs and structures of interest. Methods: Twelve adult monkeys were recruited considered healthy on the basis of history, physical examination, and general blood work. To avoid additional anesthesia, the ultrasonographic examinations were performed during routine screening, annually scheduled by the Unit of Cognitive Primatology & Primate Center, CNR-Rome, where the animals were housed. Ultrasound data were processed offline by two experienced ultrasonographers.Results: Topography, morphology and echostructure were described for almost all organs and descriptive statistics were provided.