Critical care stabilization, including crystalloid fluid therapy, cardiac stabilization, and potentially decompressive cystocentesis, should be initiated before relieving any urinary obstruction (see assessment and stabilization checklists). Because hypothermia can be found in advanced stages of urinary obstruction, the patient should be wrapped in a warming blanket. Cardiac rhythm should be assessed with an ECG and in-house stat blood work conducted to evaluate electrolytes, acid-base status, and azotemia.
If hyperkalemia is affecting cardiac function, administration of insulin and IV glucose or calcium gluconate may be beneficial. If the patient is obtunded, general anesthesia should be avoided during the initial attempt to relieve urinary obstruction Lateral abdominal radiography should also be performed to assess the causes of obstruction prior to correction.
Related Article: Urinary Obstruction in Male Cats
Hints for Urinary Obstruction Relief
For Dogs
A combination of lidocaine 2% and sterile K-Y jelly (Johnson & Johnson, k-y.com) may be mixed in a syringe and injected into the urethra via a urinary catheter after occluding the penile tip in males. Absorption of lidocaine should not cause systemic toxicity, even in patients with cardiac arrhythmias. The mixture should sit for approximately 10 minutes. This may relieve urethrospasm and increase the likelihood of flushing urethral calculi into the bladder.
If this is ineffective, general anesthesia and epidural injection of bupivacaine and morphine may be needed to relax the urethra. An appropriately sized urinary catheter is passed retrograde to the level of the urinary obstruction. A gloved finger via the rectum is used to compress the urethra proximal to the obstructing stone.
Saline is injected via the catheter to distend the urethra, then the urethral compression with the finger is released and the urinary stone flushed into the bladder. If this is unsuccessful, the process is repeated. If the stone cannot be retropulsed back into the bladder and the patient has major metabolic derangements, a temporary cystostomy tube (Stamey or nephrostomy catheter) can be inserted percutaneously into the bladder. After electrolyte abnormalities, acidosis, and azotemia have resolved, urethrostomy is performed.
For Cats
Unless the cat is obtunded, sedation or general anesthesia is usually required to relieve urethral obstruction. The tip of the penis should be massaged to loosen mucus or crystalline plugs. The penis is extruded and pulled caudally to straighten out the urethral path, and the prepuce is grasped at its reflection. A 22-gauge lacrimal catheter can be used to flush the urethra. Other options would include the use of an olive-tip catheter or an open-ended Tomcat catheter. After relieving urinary obstruction, a 3-French red rubber catheter (or other soft catheter) should be placed and connected to a closed urinary collection system.