stones (uroliths or cystic calculi) are rock-like
collections of minerals that form in the urinary bladder. They may
occur as a large, single stone or as collections of stones the size of
large grains of sand or gravel.
the same as gall stones or kidney stones?
Gallstones are in the gall bladder located near the liver, and kidney
stones are in the kidney. Although the kidneys and urinary bladder are
both part of the urinary system, kidney stones are usually unrelated
to bladder stones.
problems do bladder stones cause?
most common signs of bladder stones are hematuria (blood in the urine)
and dysuria (straining to urinate). Hematuria occurs because the
stones irritate the bladder wall causing bleeding. Dysuria occurs when
stones obstruct the flow of urine out of the bladder. Large stones may
cause a partial obstruction at the point where the urine leaves the
bladder and enters the urethra; small stones may flow with the urine
into the urethra and cause an obstruction there.
obstruction occurs, the bladder cannot be emptied and this is very
painful. Your dog may cry in pain, especially if pressure is applied
to the abdominal wall.
and dysuria are the most common signs seen in dogs with bladder stones
but with obstruction there is also pain. We know this because when
bladder stones are removed surgically, many owners tell us how much
better and more active their dog feels.
several theories of bladder stone formation. The most commonly
accepted theory is called the Precipitation-Crystallization Theory.
This theory states that one or more stone-forming crystalline
compounds are present in elevated levels in the urine. This may be due
to abnormalities in diet or due to some previous disease in the
bladder, especially infection with bacteria. Sometimes the
condition may be due to a problem with the body’s metabolism. When the
amount of this compound reaches a threshold level, the urine is said
to be supersaturated. This means that the level of the compound
is so great that it cannot all be dissolved in the urine, so it
precipitates and forms tiny crystals. These crystals stick together,
usually due to mucus-like material within the bladder, and stones
gradually form. As time passes, the stones enlarge and increase in
do they grow?
will depend on the quantity of crystalline material present and the
degree of infection present. Although it may take months for a large
stone to grow, some sizeable stones have been documented to form in as
little as two weeks.
dogs that have bladder infections do not have bladder stones. These
dogs will often have blood in the urine and will strain to urinate,
the same symptoms as a dog with bladder stones. Therefore, we do not
suspect bladder stones based only on these clinical signs.
bladder stones can be palpated (felt with the fingers) through the
abdominal wall. However, failure to palpate them does not rule them
bladder stones are visible on radiographs (x-rays) or an ultrasound
examination. These procedures are performed if stones are suspected.
This includes dogs that show unusual pain when the bladder is
palpated, dogs that have recurrent hematuria and dysuria, or dogs that
have recurrent bacterial infections in the bladder.
bladder stones are not visible on radiographs. They are said to be
radiolucent. This means that their mineral composition is such
that they do not reflect the x-ray beam. These stones may be found
with an ultrasound examination or with special radiographs that are
made after placing a special dye (contrast material) in the bladder.
bladder stones treated?
are two options for treatment. The fastest way is to remove them
surgically. This requires major surgery in which the abdomen and
bladder are opened. Following two to four days of recovery, the dog is
relieved of pain and dysuria. The hematuria will often persist for a
few days after surgery before resolving. Pets with urethral
obstruction should have surgery as soon as possible unless there are
other health conditions that prohibit surgery.
second option is to attempt to dissolve certain types of bladder
stones with a special diet. This avoids surgery and can be a very good
choice for some dogs. However, it has three disadvantages:
It is not successful for all types of stones. Stone analysis is
necessary to determine if it is the type of stone that can be
is slow. It may take several weeks or a few months to dissolve a large
stone so the dog may continue to have hematuria and dysuria during
that time. The risk of urethral obstruction remains during this
all dogs will eat the special diet. If it is not consumed
exclusively, it will not work.
bladder stones be prevented?
answer is a qualified "yes." There are at least four types of bladder
stones common in pets. If stones are removed surgically or if some
small ones pass in the urine, they should be analyzed for their
chemical composition. This will permit us to determine if a special
diet will be helpful in preventing recurrence. If a bacterial
infection causes stone formation, it is recommended that periodic
urinalyses and urine cultures be performed to determine when
antibiotics should be given. Periodic bladder x-rays or ultrasounds
are helpful in determining if bladder stones are recurring. Early
recognition may allow us to offer treatment options before your pet