Improved Longevity and Functionality of a Canine Model Providing Portal Vein and Multi-Site Intestinal Access

Background and Purpose: The canine intestinal and venous access port (IVAP) model is valuable for investigating hepatic elimination and region-specific intestinal absorption of pharmaceuticals. Previously, long-term functionality of this preparation has been variable.

Methods: Catheters of different construction were placed in the proximal and distal portions of the small intestine, colon, and portal vein of subject animals and were attached to separate subcutaneous access ports. Intraoperative, postoperative, and long-term maintenance techniques were developed, modified, and analyzed.

Results: Intestinal catheter infections and access site failures were associated with breakdown at the intestinal insertion site. The ileal catheter was prone to obstruction with ingesta. A modified Witzel technique, specialized port-catheter systems, scheduled port-flushing methods, and venous port infection treatment protocols improved the model's longevity.

Conclusions: The canine IVAP model is a powerful tool for investigation of regional differences in intestinal absorption and hepatic elimination of drugs. Other researchers can derive increased longevity with the IVAP model by using the technical modifications detailed here: strict sterile technique, closed-end slit-valve catheters, GPV^® ports, the Witzel tunnel technique, routine portal vein infection surveillance, 50% dextrose intestinal catheter infusion, rapid removal of infected intestinal catheters, and critical appraisal of their results. Longevity of the model continues to be improved.