This VETgirl online veterinary CE blog demonstrates how to unblock and treat a feline urethral obstruction (FUO). While there are numerous techniques or tips on unblocking, keep in mind that our ultimate goal is to:
- Stabilize the patient
- Treat electrolyte abnormalities (e.g., severe hyperkalemia)
- Unblock to relieve the urinary obstruction
- Provide aggressive IV fluid therapy to diurese the patient, resolve the post-renal azotemia, correct electrolyte abnormalities, and to hydrate the patient who has post-obstructive diuresis secondary to an obstruction
- Flush out the bladder
- Pain control
Treatment includes IV catheter placement, initiation of fluid therapy (No, it doesn't matter if you haven't relieved the obstruction yet!), sedation and unblocking. In feline patients with life-threatening arrhythmias secondary to hyperkalemia (including a widened T wave, bradyarrhythmia, etc.), immediate treatment with sodium bicarbonate (to push potassium intracellular) or calcium gluconate (to stabilize the heart and change the threshold potential) is imperative. VetGirl criticalists aren't huge fans of the insulin: dextrose combination - doesn't treat the hyperkalemia fast enough in our experience.
VETgirl's fav sedation: 4 mg of butorphanol total per cat, 2.5 mg diazepam, and 10 mg of ketamine IV. Sometimes this needs to be topped off with 10-20 mg total per cat of propofol. Ultimately, pick sedation that is cardiovascular sparing and allows you to safely unblock the patient.
As for the decompressive cysto. VETgirl typically does not do this unless the patient is critically ill and peri-arrest. We're pretty fast unblockers here, so can easily stabilize and unblock without having to do this. The only time we reach for a decompressive cysto is if the patient is peri-arrest or if we are having difficulty unblocking (as it relieves the back pressure on the bladder). Rarely, we've seen bladders rupture from this due to severe necrosis and ischemia to the bladder wall.
When unblocking, make sure to warn the owners of 3 main risks:
- Sedation complications
- Rupture of the bladder
- Urethral injury secondary to catheterization
Most importantly, be aggressive with IV fluid diuresis. This is imperative as some patients have a severe post-obstructive diuresis. When in doubt, monitor the ins and outs. Some cats require 40-60 mls/hour of IV fluids to help resolve the azotemia, diurese, flush out the urinary catheter line (so you can pull out the urinary catheter sooner and get the cat home),
Thankfully, most cats do well, but are at risk for re-obstruction!