Bladder stones, also known as cystoliths or urocystoliths, are a relatively common cause of lower urinary tract signs in dogs and cats. Pets with bladder stones may have painful urination, strain to urinate, have blood in their urine, or, in emergency situations, be unable to urinate altogether. Because many of these signs can also occur with urinary tract infections, the two conditions can sometimes appear very similar.
Fortunately, most bladder stones in dogs and cats can be readily identified using abdominal radiographs (X-rays), which are generally the preferred initial imaging method for diagnosis. Abdominal ultrasound may occasionally provide additional information but is not necessary to diagnose most bladder stones.
Although most pets with bladder stones have chronic or intermittent urinary signs, a stone can occasionally become lodged in the urethra and obstruct the flow of urine. Urinary obstruction is an emergency and requires immediate veterinary treatment.
Several treatment options are available for bladder stones. Depending on the type, size, and number of stones, as well as the individual patient’s anatomy, stones may be dissolved medically or removed using minimally invasive techniques or traditional surgery.
How Do We Choose the Right Treatment?
Treatment depends on several factors, including the suspected type of stone, its size and number, and the anatomy of the individual patient. While many bladder stones require removal, some can be dissolved using specific diets or medications.
Medical Dissolution of Struvite Stones
Struvite stones are the most common type of bladder stone in dogs and usually develop as a consequence of a urinary tract infection. Dissolution therefore involves both a temporary transition to a specialized urinary diet and appropriate antibiotic therapy to treat the underlying infection. Complete dissolution typically takes approximately eight weeks in dogs.
In cats, struvite stones are generally not associated with urinary tract infections. Consequently, most affected cats can have these stones dissolved with a specialized urinary diet alone. Dissolution is often relatively rapid and may occur within a couple months.
For patients with other types of stones, or when dissolution is unsuccessful or inappropriate, several options are available for stone removal. Our service offers minimally invasive techniques including voiding urohydropropulsion, cystoscopic stone retrieval, and laser lithotripsy.
Not every patient is a candidate for these procedures. The most important considerations are the size and number of stones and the anatomy of the patient.
Voiding Urohydropropulsion
Voiding urohydropropulsion is a minimally invasive technique in which fluid and controlled pressure are used to flush stones from the bladder through the urethra while the patient is under anesthesia. The procedure is typically very quick and requires no surgical incision.
The primary limitation is stone size: stones must be small enough to pass safely through the patient’s urethra. In general, stones larger than approximately 3–4 mm are less likely to be amenable to this technique, although the size that can be removed depends on the individual patient’s anatomy.
Cystoscopy and Laser Lithotripsy
When stones are too large to pass through the urethra intact, laser lithotripsy may allow them to be removed without surgery. With technique, a small camera, called a cystoscope, is passed through the urethra and into the bladder, allowing the stones to be directly visualized. A specialized laser is then used to fragment the stones into pieces small enough to be removed with a retrieval basket or flushed from the bladder using urohydropropulsion.
Like urohydropropulsion, cystoscopy and laser lithotripsy require no surgical incision and generally allow for a very short recovery period with minimal post-procedure restrictions. However, laser fragmentation can become time-consuming when numerous large stones are present. For this reason, patients with more than approximately three to four large stones may be better candidates for surgical cystotomy.
Surgical Cystotomy
Cystotomy is the traditional surgical technique for removing bladder stones in dogs and cats. It involves making an incision into the abdomen and bladder so that the stones can be removed directly.
Cystotomy remains an effective and appropriate treatment, particularly for patients with a large number of stones or stones that are too large for minimally invasive removal. The procedure is routinely performed by veterinary surgeons and is also commonly performed in general veterinary practice.
Why Consider Minimally Invasive Stone Removal?
Minimally invasive techniques, such as urohydropropulsion and laser lithotripsy, offer several potential advantages over traditional surgical removal. Most notably, these procedures do not require an abdominal incision, generally resulting in less postoperative discomfort and a shorter recovery period.
Procedures involving cystoscopy provide the additional benefit of direct visualization of the lower urinary tract. This allows us to examine the urethra and bladder during stone removal and identify other abnormalities that may be present.
Which Pets Are Good Candidates?
Unfortunately, not every patient is a candidate for minimally invasive stone removal. Whether these techniques are appropriate depends primarily on the size and number of stones, as well as the patient’s anatomy.
Female dogs and cats are particularly well suited to minimally invasive stone removal because their urethra is relatively short and wide, making it easier to pass the instruments used for cystoscopy and retrieve stones or stone fragments.
Conversely, some patients are not candidates for these procedures. Male cats, for example, are not amenable to minimally invasive stone removal because their urethra is too narrow to accommodate the instruments required for these techniques, and bladder stones are typically too large to pass naturally through the urethra.
How Can We Reduce the Risk of Stone Recurrence?
Regardless of the technique used to eliminate stones from the urinary tract, urinary stone disease should be considered a chronic condition with the potential for recurrence. Long-term prevention and monitoring are therefore important parts of successful management.
Whenever stones are removed, they are submitted to a specialized laboratory for stone analysis. Knowing the composition of the stones allows your veterinarian to develop an individualized prevention plan. Depending on the type of stone identified, recommendations may include dietary changes, additional diagnostic testing, or medications aimed at reducing the risk of recurrence.
Continued monitoring after stone removal is also important. We recommend periodic urinalyses and abdominal radiographs to look for evidence of recurrent stone formation. When recurrence does occur, identifying stones early, while they are still small, may allow them to be removed using minimally invasive techniques, potentially avoiding the need for surgery.
Referral Information
If your pet has bladder stones, or if you are a veterinarian considering minimally invasive stone removal for a patient, Dr. Palerme and the Small Animal Internal Medicine Service can review the case and help determine whether minimally invasive treatment is an appropriate option.