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The venous anatomy of the two-toed sloth (Choloepus didactylus) remains poorly understood, particularly in living specimens due to the limitations of traditional cadaveric studies. This study aims to describe the unique venous structures of Choloepus didactylus using computed tomography, enhancing our understanding of this species in a live setting. Three living Choloepus didactylus underwent CT scans as part of routine clinical assessments. The images were reconstructed using 3D Slicer software (version 5.6.2), focusing on the caudal vena cava anatomy. The reconstructions confirmed the presence of a significant intravertebral vein, showing complex venous connections through the ventral sacral foramen and vertebral foramina. These findings highlight notable anatomical variations and challenge existing literature on the species’ venous architecture. By employing modern imaging technologies, this research provides new insights into the venous anatomy of Choloepus didactylus, demonstrating the value of non-invasive techniques in studying the anatomical features of live animals, thereby offering a foundation for further comparative and evolutionary studies.

Ultrasonographic measurements of the caudal vena cava (CVC) and aorta (Ao) are known as reliable tools to assess intravascular volume status in humans. The aim of this study was to evaluate the feasibility of obtaining ultrasonographical measurements of CVC and Ao in two different views, assess intra- and interobserver variability, and study the effect of sex, age, body weight, and breed on measurements in healthy calves. The diameter and area of CVC and Ao were measured by a single investigator in two anatomic sites (subxiphoid and paralumbar window) in 48 calves aged less than 60 days and then repeated 2.5 months after the first assessment. For intra- and interobserver variability assessment, CVC and Ao measurements were repeated by three observers on five randomly selected calves. CVC and Ao measurements were easily obtained in PV and more difficult to obtain in SV. CVC and Ao area in PV showed high repeatability and reproducibility. A positive correlation was highlighted between age and CVC and Ao measurements in both sites. In conclusion, CVC size assessment by point of care ultrasound can be easily performed at a paralumbar site in calves under 4 months of age and could be used to assess intravascular volume status.

In the past, hepatic blood flow in cows was invasively characterized to investigate different pathologies and physiological conditions. However, hepatic blood flow can be easily evaluated with transabdominal Doppler ultrasound. Sixteen healthy adult non-lactating, non-pregnant Holstein-Friesian cows were examined using B-mode and Doppler ultrasound between the right flank and 9th intercostal space to establish the best approach to the different parts of the portal and hepatic vein systems, and determine normal blood flow characteristics. The main portal vein was characterized by a turbulent, high-velocity flow due to the opposing confluence of the splenic and cranial mesenteric veins, while hepatic and caudal vena cava veins have laminar blood flow, in which the phasicity is considered mainly respiratory in origin. Reference values were determined in relation to the anatomical point of observation. In conclusion, transabdominal Doppler ultrasound of the portal system is a simple technique that allows non-invasive characterization of portal and hepatic blood haemodynamics in cows.