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Name
Urethral Obstruction, Feline
Short Description
Urethral obstruction
Affected Animals: Male cats are affected most commonly. Dogs can
develop urethral obstructions as well.
Overview:
Urine flows out of the bladder through a tube
called the urethra. When debris or stones get lodged within this
tube, urine builds up and is unable to be released properly. Most
often, male cats rather than female cats develop this condition
because the male urethra, located within the penis, is narrower than
the female urethra and thus is blocked more easily. The longer the
blockage remains, the more seriously the condition threatens the
cat's health. A complete obstruction of urine flow is a medical
emergency that can result in irreversible kidney damage and death.
Some symptoms of urethral obstruction may elude owners until the cat
is severely ill. Frequent trips to the litter box, urinary
accidents, the presence of blood in the urine, and straining to
urinate are early signs that the cat is affected by a urinary tract
problem. Once a blockage has occurred, the animal will become
increasingly sick and may vomit, refuse to eat, and become weak. The
examining veterinarian can relieve the obstruction and monitor the
cat's condition until the animal is able to urinate freely.
Although diagnostic tests may identify an underlying disorder, often
it is difficult to determine all of the factors that cause a
urethral obstruction. If indicated by the laboratory results,
preventive measures such as dietary therapy and medication may be
prescribed in order to deter obstruction in the future. If the
blockage is recurring, the veterinarian may suggest a surgical
procedure in which the urethra is widened.
Clinical Signs: Clinical signs include pollakiuria, stranguria,
reduction in the quantity or quality of the urine stream, absence of
urine stream, hematuria, and urinary bladder distention. Signs of
uremia will develop in cases of complete urinary obstruction and
become increasingly severe with time. If the urinary tract ruptures
at any point, evidence of urinary leakage into the surrounding areas
may be detected.
Symptoms: Symptoms include frequent attempts to urinate,
straining to urinate, and a decreased amount of urine or lack of
urine produced by attempts to urinate. Sometimes, the urine may be
bloody. Some owners will assume incorrectly that the straining
behavior is a result of constipation. The toxic symptoms that
develop secondary to the obstruction become progressively worse with
time. These include lethargy, reduced appetite, vomiting, weakness,
a rapid but shallow breathing pattern, abnormal mental state, and
seizures. If the urinary tract ruptures, the cat may display
symptoms of abdominal pain.
Description:
The urinary tract consists of the kidneys,
ureters, urinary bladder, and urethra. The ureters and urethra are
tubes that carry the urine from the kidney to the bladder and from
the bladder to the outside of the body. The kidneys filter contents
out of the blood such as waste products and liquid. The filtered
fluid, or urine, is then sent to the bladder for storage until the
animal urinates.
If the urinary tract gets obstructed at any point, the urine will
back up in the bladder and then into the kidneys. This will result
in renal failure and a buildup of toxins in the bloodstream.
Urethral obstruction is a life-threatening emergency and should be
addressed by a veterinarian as soon as possible. The longer the cat
remains obstructed, the more likely it is to suffer irreversible
organ damage or death.
Bladder stones can cause an obstruction to the flow of urine. Also,
cats can get urethral obstructions due to a urethral plug caused by
a lower urinary tract disease. A number of interconnected factors
result in bladder stone formation. The inflammatory reaction within
the bladder, a highly concentrated urine, the presence of mineral
crystals or stones, and the production of an organic matrix
substance all contribute to the disease process. A urethral plug
forms within the small area of the urethra from the matrix and
debris from the urine that have conglomerated together. Cats that
develop lower urinary tract disease tend to form multiple plugs.
The urethra is the most common place for an obstruction of urine to
occur because of how narrow the opening becomes at distal end.
Because the urethra is narrower in the male cat than it is in the
female, male cats are especially prone to urethral obstructions.
Diagnosis: The veterinarian will diagnose urethral
obstruction after a complete history and physical exam. Diagnostic
tests are performed to investigate where the obstruction is located
and the extent of the secondary damage. Typically, the veterinarian
will order routine blood tests, such as a complete blood count, a
serum panel, and a urinalysis. Frequent reassessments will be made
to monitor the animal's response to treatment.
Prognosis: The prognosis of a urethral obstruction depends
entirely on how quickly the illness is discovered and treated. Cats
that show signs of toxicity have a serious prognosis. If
irreversible damage to the kidneys and other body systems has taken
place, the urethral obstruction can result in death.
Transmission or Cause: The development of a urethral plug is found most
commonly in the male cat. The plug usually is comprised of a mucoid
matrix that gels with urinary tract cells, inflammatory cells, and
crystals of minerals. The exact cause of the predisposing urinary
tract disorder is not fully understood, but is a subject of
investigation by veterinary researchers. Also, urethral obstructions
can occur due to a stone blocking the flow of urine.
Treatment:
Treatment for a complete urinary obstruction, a
life-threatening emergency, should be instituted immediately to
prevent permanent damage. The examining veterinarian will have a
high suspicion that the animal is obstructed from the history and
physical exam. Diagnostic tests usually are postponed until the
obstruction is relieved and the cat is stabilized.
Most cats will need to be heavily sedated or anesthetized to allow
the veterinarian to correct the obstruction. One method of
obstruction relief involves palpating the urethra in the attempt to
dislodge any urethral plug that may be present. In most cases, a
urinary catheter is inserted into the urethra and sterile saline is
injected to flush material back into the bladder. The catheter is
then inserted into the bladder to allow the urine to drain
completely. In order to remove debris from the bladder and to soothe
the irritated bladder lining, the veterinarian will flush out the
bladder with cool, sterile saline until the fluid retrieved remains
clear. The catheter is then sutured to the outside of the body and
left in place for some time so that the bladder size will remain
small. The veterinarian will determine when the urinary catheter
should be removed.
There is a possibility that the cat will obstruct again soon after
the catheter is removed. Thus, most cats with obstructions remain
hospitalized to allow for close monitoring. The inability to control
urination is considered a warning sign. Due to the amount of
stretching that can occur when an animal is completely obstructed,
the bladder may be incapable of contracting for some time.
Medications can be administered to help this condition once the risk
of re-obstructing has decreased.
In order to counteract the toxic effects of urinary tract
obstruction, intravenous or subcutaneous fluid therapy will be given
to the cat. Fluids help correct any dehydration and electrolyte
abnormalities. For the cat that has been obstructed long enough to
result in renal compromise, intravenous fluids are continued at
fairly high volumes for two to five days. Unfortunately, some
patients suffer irreversible kidney damage due to a prolonged
obstruction.
Other medications such as antibiotics are used as needed in cats
with bacterial infections. If crystals or bladder stones are
present, appropriate medications or diets will be recommended.
Surgery sometimes is required for animals that have certain types of
bladder stones. A surgical procedure to enlarge the urethral opening
at the outside of the body may be required for those cats with an
obstruction that can not be relieved by other methods. This
procedure also may be performed on cats that have recurrent
obstructions despite appropriate medical therapy and preventive
measures. This surgical procedure, called a perineal urethrostomy,
requires that the cat be neutered to allow access to the urethra.
The distal part of the penis is removed and the more expanded
section of the urethra then is opened up and sutured to the
surrounding skin. A perineal urethrostomy will decrease the
likelihood of future obstruction but will not prevent the symptoms
of cystitis or lower urinary tract disease that already may be
present.
Prevention: An attempt should be made to diagnose and prevent
any potential causes of urethral plug or stone formation. For
certain cats with urethral obstructions, prescription diets or
medications may be recommended. Encouraging the cat to drink water
more frequently may aid the bladder to flush out some of the debris.
Some cats will drink more water if there is a source left running
such as a dripping faucet or water fountain. Recurrence of
obstruction may require surgical enlargement of the urethral
opening.
