Maximizing the success of bile duct cannulation studies in rats: recommendations for best practice.

Bile duct cannulation (BDC) studies are usually carried out in the rat to support the absorption, distribution, metabolism and excretion profiling of novel agrochemicals and pharmaceuticals. The different aspects of these studies (e.g. surgical preparation, dosing and collection of bile) can be intricate and/or technically complex. The animals are often kept singly housed for the duration of the studies following surgical implantation of the cannulas. The generation of insufficient data to meet the study objectives, for example due to failure in cannula patency, can result in the need to repeat these studies. A working group of contract research organizations that routinely carry out BDC studies was brought together by the National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs) to share their experiences, and to establish the key factors necessary to ensure routinely high success rates. Through these discussions the group has identified opportunities for best practice across various aspects of the studies. The aim of these recommendations is to support all staff involved in conducting BDC studies to maximize the amount of useful data generated using the fewest animals possible, while ensuring the highest possible standards of animal welfare.