In cats that are difficult to unblock, we use the soft portion of a 22-ga intravenous catheter and sterile saline solution
in a 3-ml Luer lock syringe. The force that you can get with an intravenous catheter seems to be stronger than other options
and is relatively atraumatic. If we are unable to unblock the cat using sterile saline solution, then we use a mixture of
lubricant and saline solution that, with time and persistence, always works. By using these two methods, we haven't yet encountered
a cat that we have been unable to eventually unblock relatively atraumatically.
Dr. Bill Feeman