Blood donation is a topic not just restricted to humans, although our understanding of the requirements and limitations of donating blood is well recognised here. A study published by Marshall KA et al., ‘Ultrasound measurements of the caudal vena cava before and after blood donation in 9 greyhound dogs.’ in The Canadian Veterinary Journal in Sep 2018 (59(9):973-980) addresses this topic, and the abstract will be the focus of this article. The caudal vena cava is responsible for carrying deoxygenated blood from the body back to the heart, and this research looked at any changes in the diameter of this vessel before and following blood donations in order to monitor any differences in intravascular volume. Nine Greyhounds were used as models in this study, and ultrasound imaging was used to assist in determining the diameter of the caudal vena cava. The results revealed that there was a significant difference in the measurements before and following blood donation, alongside a reduction of 8% of intravascular volume. However this difference is considered small, and the authors highlighted the importance of extrapolating these findings to real-life situations, namely that this reduction would be unlikely to translate over. In other words, even if there was a change it would be too small to be easily realised physiologically. It is important that we always keep this in mind – scientific studies are beneficial in allowing us to monitor cause and effect, but this may not always occur in a clinical/physiological setting. If you’re looking to use ultrasound imaging in small animals such as dogs, take a look at our website or feel free to contact us for more information.