Meet Romeo, a 5 year old neutered male cat.  He is the king of
his household and a very sweet boy.  I have known Romeo and
his sisters for approximately 5 months.  One evening while sitting
for him, I came in and Romeo was not acting himself.  He did not
greet me as was normal for him and instead paced around
meowing.  I looked at him and knew something was not  right.  I
was talking to him, asking him what was wrong and he looked up
at me with a look that said "please help me".  He was meowing
forlornly, was drooling from the mouth and appeared weak.  He
tried to make his way to the litter box and collapsed.  I immediately
felt his abdomen and noted an extremely large bladder - Romeo
could not urinate.

I immediately rushed him to the Emergency Room and called his
owner's en route.  They were over 2000 miles away and trusted
me to do my best for Romeo in their absence.  At the Emergency
Room, the veterinarian was able to empty Romeo's bladder by
placing a catheter. When he took x-rays, several small stones
were seen in Romeo's bladder.  One of these stones had made
it's way into Romeo's urethra and had effectively "blocked" the
urine from exiting the body.  This was an emergency situation and
Romeo was immediately hospitalized, placed on IV fluids and the
necessary tests were performed.  

As you can imagine, not being able to urinate is quite painful but
what you may not know is that it is deadly.  If left untreated,  toxins
build-up in the blood, the kidneys start failing or shutting down,
heart arrhythmias start and death eventually follows.  Romeo's
blood work revealed that his kidneys had started to shut down
and he was in a metabolic crisis.  The IV fluids would help
rehydrate him, diurese or "flush" his kidneys and help normalize
his electrolyte balance. The urinary catheter would maintain an
open exit for the urine but the stones still in the bladder needed to
be removed.  

Romeo did have extensive surgery and a lengthly hospital stay,
but eventually made a full recover from this crisis and returned to
his loving family.  However, had he not been taken to the
veterinarian when he was, he may have not been able to be
saved. In other words, if I had only been visiting Romeo every few
days, Romeo would probably not be alive today.

This illustrates why it is so important to have your pets checked at
the minimum of once daily while you are away.  
Romeo a few days before his crisis - it's important to note
that Romeo showed no sign prior to this episode that
anything was amiss even though the veterinarians agreed,
this had been a chronic on-going situation.
Romeo at the hospital waiting for surgery
For more information about urinary
blockage in cats, please visit this website