Bladder Stones

By Dr. Karen Burgess

What is a bladder stone?
Uroliths or bladder stones are the accumulation of minerals in the urinary tract that form rock like structures. Bladder stones can range in size from the size of sand to as large as an orange. There are many different types of bladder stones and they are described based on their mineral makeup. Bladder stones can take days to years to develop and can be a one-time only or chronic condition.

What are common signs and problems associated with bladder stones?
Bladder stones often abrade or rub the bladder wall causing irritation. This can lead to blood in the urine and decreased ability to fight off bacterial infections. In severe cases the stone can block the passage of urine out of the bladder causing the bladder to distend and potentially causing life-threatening complications. Owners will often note that their pet has increased urgency to urinate, is urinating more frequently, or having accidents in the house. In some cases the pet may posture to urinate frequently but have a poor stream of urine (dribbling). Pain, inappetance, vomiting, and collapse can all develop with more severe disease.

What causes bladder stones to develop?
The type of stone often helps determine the underlying cause along with the patient’s age, sex, and breed. Some stones (struvite/triple phosphate) are almost exclusively secondary to bacterial infection of the bladder. Other types such as urate or cystine have a genetic correlation with certain breeds having a higher incidence. There are also many cases in which there is not a direct cause and effect in a patient and for whatever reason (physical, metabolic, physiologic) a pet is predisposed to stone formation. Diet has been associated in the past with some stone formation and often diet manipulation is essential in preventing or treating bladder stones.

How is my pet diagnosed with bladder stones?
In some cases larger stones can even be palpated on physical exam. The definitive diagnosis of bladder stones involves visualizing the stones typically via radiographs or ultrasound. While ultrasound may be more expensive at face value, some stones due to their mineral composition or size are not readily visible on radiographs while they would be apparent on ultrasound. Since many pets present initially with symptoms of a urinary tract infection (straining, bloody urine), initial testing often involves collection of urine for examination. This urine sample needs to be sterile or collected directly from the bladder with a needle (similar to a blood draw). Performing a culture on the urine allows diagnosis of specific bacterial infections if present.

What is the treatment for bladder stones?
The treatment for bladder stones depends largely on their specific composition. For some, specific prescription diets will dissolve even existing stones. For other stone types physical removal is necessary either via surgery or a procedure where the stones are expelled with compression of the under anesthesia. In cases of urinary tract obstruction due to a stone immediate intervention either with catheterization or surgery may be necessary.

How are bladder stones prevented?
The specific stone type determines how best to prevent recurrence. Increasing water intake and thus diluting the urine is appropriate for all types of stones. Manipulation of urine acidity via diet or medication is also utilized in many cases. Monitoring for bladder infections that may be silent and periodic radiographs or ultrasound to look for “silent” stones may also be recommended. The ultimate goal is to detect stones at a time where intervention other than surgery is an option.