Some problems affecting our best friends sound like lessons out of a medical textbook, but bladder stones are just what they seem – stones found in the bladder. Despite their straightforward name, these stones are undesirable because they can cause quite a bit of irritation in the bladder, and occasionally they can find their way out of the bladder to the urethra, where they cause life-threatening obstructions.

Bladder stones form in the bladder when conditions are favorable. Sometimes there are hereditary reasons (just like in humans), and sometimes chronic infections or metabolic diseases are to blame. According to the Winn Feline Foundation, up to 13% of cats with lower urinary tract disease today have uroliths (bladder stones).

There are several different types of bladder stones, but let’s focus on the four most common:

Calcium oxalate

These are the stones that seem to have a hereditary component. We find them in middle-aged to older pets, and there are certain dog breeds that are more prone, such as the Miniature Schnauzer, Lhasa Apso, Yorkshire Terrier, and the Bichon Frise.

Infection-induced struvite stones

As their name implies, these stones are most often caused by bladder infections. Some kinds of bacteria that cause bladder infections produce urease, which alters the pH of the urine, making it favorable for the formation of struvite stones. Struvite stones associated with infection are most common in dogs, and will cause recurrent urinary tract infections.

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Sterile struvite stones

These are more common in young cats. Thankfully, veterinarians are seeing less and less of these stones as food formulations change to try to prevent them.

Urate stones

Urate stones are caused by an increased excretion of urates in the urine. Dalmatians and Bulldogs are affected by urate stones more frequently than other breeds. In addition, liver disease (such as liver shunts or cirrhosis) can cause urate stones.

Bladder stones may be suspected if your pet has chronic urinary tract infections, bloody urine, or discomfort during urination. Male cats are especially prone to urethral blockage from stones due to their narrow urethras. Blockage of the urethra (the passageway for urine out of the body) is life-threatening in any animal.

Struvite stones can often be dissolved by placing your pet on a special diet, but if the stones are posing a threat it’s best that they are removed surgically as well. Because surgery is often necessary in cases of bladder stones, having

Preventing bladder stones

Struvite stones can be prevented by controlling urinary tract infections and by feeding a diet that creates a more acidic urine. Unfortunately, there is no good way to control calcium oxalate stones. Special diets are available that may allow the stones to form more slowly, but they will still form over time. In the case of urate stones, the underlying cause should be addressed to help prevent stone reformation.

If chronic urinary tract infections are plaguing your pets, your veterinarian’s office is just a stone’s throw away!

Sep 12, 2011
Pet Health

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