What are bladder stones?
Bladder stones (urinary calculi) are rock-like collections of minerals that form in the urinary bladder. They may be in the form of a large, single stone or as multiple small stones like sand or gravel.
Why are they a problem?
The stones may cause an obstruction in the urine path, making your pet strain without passing any urine. They can also cause trauma to the lining of the bladder or urethra, resulting in the production of bloody urine.
When the bladder is obstructed, it cannot empty its contents. This is uncomfortable and extremely painful. Pets may cry in pain, especially if their abdomen is pressed. They may also lick at their genital area.
How do they form?
There are many causes of bladder stone formation. High concentrations of minerals in the urine can cause the small mineral particles to collect together and form stones. The increased levels of these minerals can be diet-related, or as a result of previous bladder injuries (like infection). Abnormalities in body metabolism can also cause increased mineral levels in the urine.
How are they diagnosed?
Some bladder stones can be felt through the abdominal wall in a physical examination. However, not all are found this way. Most bladder stones are visible only through X-ray or ultrasound. Sometimes, a contrast dye must be placed in the bladder before taking an X-ray for a more accurate diagnosis. Ultrasound examination is a very sensitive way to visualize both large bladder stones and the sand/gravel (small stones) that can also form. Cystitis (bladder infection) will cause similar signs to bladder stones, so only a professional diagnosis will determine the condition.
How are they treated?
There are two ways to remove bladder stones. The fastest is via surgery. The bladder is opened and the stones are removed. Surgery is essential if there is an obstruction in the bladder or infection associated with the stones.
You can sometimes treat less severe bladder stones with a prescription diet. However, there are three main disadvantages to this method:
1. it is not effective on all types of stones
2. it is slow to work, prolonging your pet’s pain and discomfort
3. not all pets will eat the prescription diet, and it must be fed as a sole food source or it will not work
Can they be prevented?
Yes. If stones are removed surgically or if small ones are passed in the urine, they should be analysed. This will tell us if the use of a prescription diet will be helpful in preventing further stone formation. Regular urine tests will be required to monitor for any signs of recurrence. Antibiotics may need to be used intermittently to treat bacterial infections.