Many people are familiar with kidney stones. Well, dogs and cats get these too, but they are more likely to get bladder stones. If the bladder stones are too big to pass through the urethra, they may get stuck, and that is when we have in an emergency situation.

Bladder stones are compared of mineral deposits in the bladder. There are many different types of bladder stones, but three are common: struvite or triple phosphate stones, calcium oxalate stones and urate stones. The names reflect the composition of each stone. So, a calcium oxalate stone is just that, made up of calcium and oxalate; triple phosphate stones are made of magnesium, ammonium and phosphate; and urate stones come from deposits of uric acid.

Bladder stones have a propensity to form in different bladder environ ments. The pH of the urine can play a role in which stones form. Triple phosphate stones are more likely to form in an alkaline pH of urine. The opposite holds true for calcium oxalate stones that form from acidic pH. Urate stones tend to form as the result of uric acid build-up in the urine being stored in the bladder. It’s not as if you will be toting around a ‘pee pH detector’ to check your pet’s urine, but knowing it can be useful in diagnosis and treatment. Leave that up to your Doc.

Some breeds of dogs and cats are predisposed to suffering from bladder stones. Calcium oxalate stones really like miniature schnauzers. Lhasa apsos, Shih Tzus and Yorkshire terriers have a propensity to make these stones, too. Urate stones are the most prevalent in Dalmatians. Triple phosphate stones are the most common and can form in any breed. They also are very common in cats. Calcium oxalate stones in cats seem to favor some Asian breeds like the Himalayan and Persian varities.

Another predisposing factor to the formation of stones can be bladder infections, which can change the pH of the urine, and thus precipitate crystal formation. The crystals can aggregate into clumps that attract more crystal adherence, resulting in a stone or stones. Other causes of pH change also can help promote stone formation—even diets that result in an acidic or alkaline urine.

Usually, the initial symptoms you see in pets with bladder stones mimic those of a urinary tract infection: frequent urination, urinating in the house, straining to go with hardly any urine coming out, and painful urination are the usual suspects. You may find yourself punishing your pet for going in the house when it is not their fault. Blood in the urine is an obvious tip off that something is very wrong with your dog or cat. Sometimes your vet will be able to feel the bladder stones at the time of examination, but usually it requires an X-ray or ultrasound to diagnose.

Stones are most damaging when they get stuck in the urethra on the way out. Too big and they’ll just hang out in the bladder, causing their own brand of trouble; too little and they will pass. It is the ones that only make it halfway out that will create an obstruction, which can cause a lot of trouble relatively quickly and require immediate attention. This condition can be very painful and may cause your pet to cry out when straining to urinate.

So, if your pet seems ‘not right’ and is peeing all over the house, waking up in the middle of the night to go out, squatting repeatedly without producing a full stream, it is time to see the vet. Do your level best to collect some urine prior to your appointment. Often, that sample is the ‘liquid gold’ that results in a more accurate diagnosis than all of the symptoms and examination combined.

Dr. Kenneth Geoghegan, of Village Veterinary Hospital in Warson Woods (, has been a neighborhood veterinarian since 1992.

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