Novel drug sampling technique: portal vein catheterization in steers.

Objective: To determine the feasibility of catheterizing the portal vein to obtain serial portal vein blood samples in steers. We hypothesized that the portal vein catheterization would be a successful continuous sampling technique with minimal adverse effects in steers.

Methods: 2 groups of steers were used: a pilot group (n = 2) and experimental group (n = 6). In both groups, steers were sedated with xylazine. The right rib spaces were clipped and aseptically prepped. The portal vein was visualized via ultrasound, and a 14-gauge catheter was placed percutaneously and advanced into the portal vein. A guide wire was passed through the catheter, followed by a tissue dilator and then a vascular balloon catheter. In the pilot group, blood chemistries were performed prior to portal vein catheterization and then again once the catheter was placed (with samples from both the jugular vein and portal catheter). The liver was also examined at necropsy for any gross lesions in both groups.

Results: All steers tolerated the portal vein catheters well, with the catheters lasting for the full length of the study period (7 days). The only observed adverse reaction was a superficial abscess at the catheter site (n = 3). On necropsy, 1 liver had gross discoloration, but no other abnormalities were noted. There were no significant changes in biochemistry profiles before or after portal vein catheterization.

Conclusions: Portal vein catheterization is a novel and feasible serial sampling technique of the portal vein.

Clinical relevance: This technique can be used in future pharmacokinetic, nutrition, metabolism, or toxicity studies.