Hi someone sent an earlier mail regarding attaching old used drip bags with new giving sets to urinary catheters - not a well known fact but make sure each drip bag has had suction applied with extracting at  least 40mls (may need more in Dgs) of air (use syringe & needle in injection port of drip bag to do this) before leaving bags to collect urine - this will create instant vacuum pressure & will prevent retrograde hydronephritis & allow urine to drain faster & therefore your patient much more comfortable!!! Male cats also benefit from having the giving set taped to their tails to prevent potential drag on their prepuce!!!