Description of an ultrasound-guided technique for blood sampling from the cranial vena cava in anesthetized guinea pigs (Cavia porcellus)

Abstract

TThe anesthesia-related mortality rate is higher in guinea pigs than in dogs or cats ( Brodbelt et al., 2008 ), which could be related, among other causes, to inadequate assessment of the health of each individual and difficulty in monitoring cardiopulmonary variables during anesthesia ( Hawkins and Pascoe, 2020 ). Blood sampling for hematologic or serologic tests is complicated by the small size of these animals and the stress induced by handling. Auricular veins, the lateral saphenous or the tarsal veins can be used to obtain small volumes of blood ( Birck et al., 2014 ). The jugular vein is neither visible nor palpable in guinea pigs. Although the ‘blind’ (landmark-based) puncture of the cranial vena cava may yield a higher blood volume, iatrogenic injury of adjacent structures (pleural, mediastinal or cardiac puncture) may occur. Blood sampling from the jugular vein or the cranial vena cava is usually performed in guinea pigs during anesthesia to reduce stress and improve handling. Ultrasonography is commonly used in veterinary anesthesia to identify nerves (as well as the adjacent anatomic structures such as blood vessels) to perform locoregional techniques ( d'Ovidio and Adami, 2019 ). Ultrasound-guided vascular access is relevant in some situations in veterinary practice ( Chamberlin et al., 2013 ; Hundley et al., 2018 ). Ultrasound imaging allows visualization of the vessel by identifying associated anatomical structures and the course of the advancing needle or catheter. Facilitating the ease, speed and safety of blood sampling in guinea pigs may encourage more routine laboratory testing and contribute to health status assessment.