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Client Library Article
BLADDER STONES (CYSTIC CALCULI) in
Dogs & Cats
| Types & Formation of
Bladder Stones |
| The formation of bladder stones, also referred to as cystic
calculi, and urine crystals is a common condition seen in both dogs
and cats. The three most common types of stones are struvite (triple
phosphate), calcium oxylate, and uric acid stones, although there are many
other types that can form. In dogs, certain breeds are prone to developing a
particular type of stone. Dalmatians are predisposed to
forming uric acid stones due to a genetic defect in uric acid metabolism
leading to a much higher concentration of uric acid in the urine. Dogs with
liver shunts are also at a higher risk for uric acid stone formation.
Struvite and calcium oxylate stones seem to be more prevalent in small breed
dogs, especially Miniature Schnauzers, Lhasa Apso's, and Shih Tzu's.
In cats, the stones are commonly struvite (triple phosphate) or calcium
oxylate.
Stones & crystals form in the kidneys or bladder when high concentrations
of minerals precipitate out of urine. Struvite stones & crystals form when
the urine is very alkaline (pH greater than 7) whereas calcium oxylate and
uric acid stones and crystals form in acidic urine (pH less than 7). Bladder
stones & crystals in the urine are important to treat for they can lead to
urinary obstruction- a life threatening condition. |
| Symptoms-
Pets with bladder stones often have no clinical signs other than frequent
urinary tract infections. |
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Symptoms of a urinary tract infection include:
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| Diagnosis of Bladder
Stones |
- Bladder stones- rarely can be palpated. A radiograph
(x-ray) is required to look for stones in the urinary tract (kidneys,
bladder, & urethra).
- Calcium oxylate and struvite crystals are radio-opaque and show up
easily on normal radiographs
- Uric acid stones are radiolucent and will not show up readily on
regular films. A special contrast x-ray study must be performed to
show uric acid and other radiolucent stones.
- Ultrasound of the urinary tract is useful to look for stones in the
kidneys, bladder, urethral neck
- Urinalysis- look for infection & crystals- if present, check for
urinary tract stones
- If a stone is retrieved surgically, it should be identified via stone
analysis.
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| Treatment of Bladder
Stones (cystic calculi)- Medical Vs Surgical management |
- Medical management- Many pets with
crystals in their urine can be treated medically by placing them on a
special diet designed to dissolve existing crystals and prevent future
crystal & stone formation by limiting mineral intake and manipulating
urine pH.
- Some bladder stones will dissolve with special diets, but the majority
require removal via surgery
- Patients with concurrent urinary tract infections should also be
treated with antibiotics.
- Surgical management- via cystotomy surgery-
Most patients with large identifiable bladder stones on radiographs
eventually require surgical removal. Large bladder stones often do not
dissolve completely and it is recommended that they be surgically removed.
If the stones are not removed, at some point they are likely to pass into
the urethra during urination and become lodged causing a urethral
obstruction.
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| Prognosis |
- Good to fair depending on concurrent problems such as UTI.
- Urine pH needs to be strictly monitored and a special diet should be
fed for life in pets prone to forming stones, crystals, and urinary
blockages
- Some individuals continue to form despite the most appropriate medical
management
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