Urinary Tract Infection And Bladder Stones

Signs of a urinary tract infection include blood in urine, accidental urination in the home or straining to urinate.  After a complete physical exam, a sterile urine sample is collected for urinalysis and culture.  A urine culture allows for the determination of the best antibiotic to treat the bladder infection.  The urine sample is also screened for crystals.  If they are seen, it is best to get an x-ray to determine if bladder stones are present.   If they are, bladder stones must be addressed in order for successful resolution of the bladder infection.

There are several types of bladder stones which can form in the body. If the pet has struvite bladder stones, these are often predisposed by a bladder infection. Most bacteria in the bladder gain access by crawling up the lower urinary tract.  The mineral compositions of bladder stones may call for different treatments.   Struvites are formed by an enzyme called urease that certain bacteria can produce.  In an alkaline pH, the presence of this bacteria can trap struvite crystals and gels into a stone.

Bladder stones can be removed using different techniques, each with its pros and cons.  If the stones are small enough to pass through the urethra, a voiding urohydropropulsion is done.  This technique requires the patient to be deeply sedated or under general anesthesia; and is not ideal if there are many large stones.

Surgical removal is the most direct method.  This method requires general anesthesia, hospitalization and recovery time.  If we wish to avoid surgery and the stones are small enough, a cystoscope can be passed into the patient’s bladder and the stones retrieved with a basket. This method requires specialized equipment and must be referred to a specialty practice.

In most cases, struvite stones allowed for dietary dissolution treatment.  A prescription therapeutic diet was chosen for this purpose.  It is designed to dissolve struvite bladder stones by creating an environment in the bladder which is not favourable to struvite stones. The advantage to the dissolution method is that it is the most comfortable approach for the patient.  We would need to be careful because as the stones gets smaller, there is a possibility that they can get lodge in the urethra, especially if the stones are too large to pass during the act of urination.  This will cause a complete urinary obstruction, which can be life-threatening, if not addressed immediately.

To be effective, the prescription diet must be the only food fed until the stones are dissolved. Antibiotics  are needed as long as stones are in the bladder (bacteria are encrusted within the stone and as the stone dissolves, they are released).  An x-ray is taken approximately every 4 weeks to ensure that the stones are getting smaller.  Repeat samples for urinalysis and culture are also done to ensure the proper urinary conditions for dissolution.

It will typically take 2 to 3 months to dissolve the stone(s) and as long as the patient is otherwise healthy, the diet should be continued long-term.  Since struvite stones are predisposed by the urinary bacteria, controlling the infection is key to prevent recurrence.   After the stones are dissolved, periodic urinalysis and cultures are performed to check for infection recurrence.