These 32ga (0.8Fr) PU (polyurethane) catheters are the gold standard for intrathecal injections in rats. The implanted segment is .010in (250 micron) OD polyurethane. It transitions to a polyethylene (PE) segment that connects to a 27ga
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Pogatzki EM, Zahn PK, Brennan TJ. Lumbar catheterization of the subarachnoid space with a 32-gauge polyurethane catheter in the rat. Eur J Pain. 2000;4(1):111-3.
Having a reliable connection between a surgically implanted catheter and an external device is critical in laboratory animal research. Read this study on reasons for unwanted catheter disconnection.