Maximising the success of bile duct cannulation studies

BDC studies are usually carried out to help determine how new agrochemicals and pharmaceuticals are absorbed, distributed, metabolised and excreted. They are conducted to meet regulatory requirements before new products can be registered and marketed. Following dosing of the drug or chemical, bile is collected from the rats at regular intervals, and analysed to determine the level of drug/chemical present. These studies require that rats have cannulas implanted into their bile ducts to allow for repeated bile collection, which may need to take place over many days. The different steps within these studies, which include the surgical preparation, dosing and bile collection, can be intricate and/or technically complex. The animals are often kept singly housed following surgical implantation of the cannulas, which helps to ensure that their cannulas are kept intact. If insufficient data is generated to meet the study objectives, for example due to inadequate bile collection resulting from blockages in the cannulas, the studies may need to be repeated.

In an NC3Rs-led initiative, an expert working group of CROs that routinely carry out BDC studies was brought together to share their experiences. The aim was to establish the key factors necessary to ensure that BDC studies are successful and that high standards of welfare achieved. Through these discussions, the group identified opportunities for best practice across the various aspects of the studies, which are described in the new report. These include: consideration of whether a BDC study is necessary in the first instance; the need for good record keeping and logical troubleshooting; ensuring that animals fall within the optimum weight range before undergoing surgery; aspects linked to the surgical technique such as cannula placement; the need for careful handling following surgery; and the minimisation of the time animals are kept singly housed.

This work was presented as a poster at the LASA 2016 winter meeting, where it was highly commended. We welcome feedback from practitioners in the field who are conducting these studies and have identified additional techniques and key factors that impact on their success rates.

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