Mucus, crystals and even tiny bladder stones can clump together to form a plug in the narrow male cat urethra. The opening is so small that it does not take a lot to completely or even partially obstruct urine flow. Only a few drops of urine are produced or sometimes no urine at all is produced. Male cats in particular are at risk for this life-threatening complication. This is because the female urethra is shorter and broader and thus far more difficult to obstruct.
Urinary Blockage is an emergency. Initial signs include straining to urinate, bloody urine, inappetance, vomiting and lethargy. If the obstruction persists 3 to 6 days, the toxin build up will result in death.

The bladder is often the size of a peach and very firm when palpating the abdomen. Attempts to express the bladder are often unsuccessful confirming urinary tract obstruction. Rarely, gentle pressure on the bladder will result with expulsion of the blockage. Blood work often reveals elevated kidney values and alterations in electrolytes. The variation in blood work is due to urinary toxin build up from the inability to urinate. This causes vomiting, lethargy and cardiac arrhythmias. Abdominal radiographs are performed to assess if bladder or urethral stones are present.

A urinary catheter is placed through the urethral opening while concurrently pulsing saline solution through the urinary catheter to move the obstruction back into the bladder. This procedure is often painful and sedation is most always needed. The degree of difficulty varies when unblocking a cat. Some cats cannot be unblocked and must have an emergency perineal urethrostomy to re-establish urine flow.
Once unblocked, the bladder is flushed with saline to remove crystals, inflammatory debris and blood. The urinary catheter is then sutured in place and will stay in place for a couple of days. A urinary collection bag is attached to the catheter so that urine production can be measured. The patient is placed on intravenous fluids to correct dehydration and diurese the kidneys. Once urine flow returns, the kidneys quickly begin to correct the metabolic disturbances that have been taking place. The urinary catheter is removed after a few days and the patient is observed. The patient is not discharged until he is able to urinate on his own.
It is vital to realize that the cat is at risk for re-blocking for a good week or two from the time of discharge. This is because the irritation that led to blocking in the first place is still continuing and as long as the episode continues, blocking is a possibility. It is crucial that the patient is monitored closely at home to ensure urinating readily. Urinary blockage can be prevented by increasing water consumption or feeding solely canned food. Other dietary changes may also be required in the case where blockage is a result of crystals or stones.  When urinary blockage becomes recurrent in a male cat, a perineal urethrostomy (PU) should be considered. This consists of surgical reconstruction of the genitalia to create a more female-like opening. Basically, the penis is removed and a new urinary opening is made.

Case of the month:
Patient is a 1y male intact DSH that presented for straining not eating and vomiting. The patient has a history of urinary obstruction 6 months prior. A urinary diet was recommended at that time, but was not fed consistently. Upon physical examination the patient had a large firm bladder that was painful and unable to be expressed. Blood work revealed elevated kidney enzymes. A large bladder was apparent on abdominal radiographs and no stones were seen. Urinalysis revealed increased number of white blood cells and a marked number struvite crystals. The patient was sedated and a urinary catheter was passed. The bladder was flushed with saline solution. The urinary catheter was sutured into placed and a collection bag attached. The patient was placed on intravenous fluids, given pain and antibiotic injections. The patient was transferred that evening to an emergency referral center for further monitoring and treatments throughout the evening. The urinary catheter was removed 2 days later and the patient was discharged later that day after he was urinating on his own.  The patient was dispensed samples of urinary food at discharge to prevent any further crystal formation.