External jugular vein catheterization technique for continuous blood sampling in gilts

External jugular vein blood collection is common in gilts and sows, but continuous sampling for hormonal and pharmacokinetic research requires catheterization. The standard protocol has remained largely unchanged for nearly 40 years. This study aimed to develop a modified external jugular vein catheterization technique in gilts. Ten gilts (72.0 +/- 3.4 kg) underwent surgery under general anesthesia after 12-hour fasting. Sedation was induced with intramuscular Xylazine (4.4 mg/kg) and Tiletamine-Zolazepam (2.2 mg/kg), followed by intravenous Thiopental sodium (10 mg/kg). Once anesthetized, gilts were placed in dorsal recumbency, and the external jugular fossa was prepared under sterile conditions. A 10 cm incision was made above the external jugular vein, and connective tissue was carefully cleared. A cranial ligature blocked blood flow, and a 0.5 cm longitudinal incision was made caudally on the external jugular vein wall. A #5 feeding tube (50 cm) was modified as a catheter with three external rings for fixation. One ring was placed at the exit site, another inside the vein, and the third at the fixation point. The internal ring was secured with 3-0 vicryl sutures to ensure blood flow. The catheter was flushed with heparinized saline (10 IU/ml) to prevent clotting and routed subcutaneously before incision closure with 3-0 monofilament nylon sutures. After a 48-hour recovery, the catheters remained functional for at least 4 days, ensuring sample quality and procedural success. This modified technique enhances continuous blood sampling feasibility in gilts.