The author acknowledges the prior contribution of Fairfield T. Bain Hagyard Equine Medical Institute, Lexington, KY, USA
Jugular Vein
The jugular vein is often evaluated ultrasonographically, particularly when thrombophlebitis is suspected in horses with or without intravenous catheters in place. Early signs of thrombophlebitis can be detected ultrasonographically prior to any obvious external indication, including thickening of the wall and/or clot formation. Ultrasound examination of more advanced cases might show partial or complete blockage of the vein and abscess formation. Perivascular injection of medications may cause a local reaction including a focal cellulitis or abscessation (Figures 26.1, 26.2, 26.3, 26.4, 26.5, 26.6, 26.7, 26.8, 26.9, 26.10, 26.11, and 26.12). The jugular vein can be imaged along the neck from its entry into the thoracic inlet distally throughout its course to the bifurcation into the internal and external jugular vein branches just caudal to the ramus of the mandible. To facilitate evaluation, the jugular vein should be distended by occlusion distally near the thoracic inlet, and then the probe can be used to trace the vein along its course. Thorough evaluation involves imaging in both longitudinal and transverse planes. The author likes to scan from distal to proximal along the vein with particular focus on the region of concern (e.g., site of intravenous catheter insertion or palpable thickening of the vein or perivenous tissues).