CANINE BLADDER STONES (UROLITHIASIS)

What are bladder stones?

Bladder stones, or uroliths, are stone-like mineral deposits that form in the animals urinary bladder. Bladder stones may occur as a single deposit, or consist of many smaller pieces. They can be large and take up most of the bladder, or be fine particles that are passed when the animal urinates.

Are bladder stones the same as kidney stones?

Kidney stones are mineral deposits that occur in the kidney. They are not as common as bladder stones and may not require immediate attention as bladder stones do. Kidney stones are usually not related to bladder stones.

Can bladder stones cause a problem for my pet?

Yes, the two most common signs of bladder stones are blood in the urine, and straining to urinate. The blood is the result of the stones rubbing against the bladder wall. The straining results from the irritation to the bladder and urethra, or from small stones or sand passing out of the bladder when the animal urinates If the stones move out of the bladder and get stuck in the urethra an obstruction occurs. This is a painful, life threatening condition. If the obstruction is not quickly relieved the bladder can rupture, and the animal will die. If you suspect a problem you should contact your veterinarian immediately

Are all bladder stones the same?

No, there are several types of bladder stones. One of the most common is called struvite. These stones consist of Magnesium, Ammonia, and Phosphorus. Another is the urate stone. These are commonly found in Dalmatians that have a genetic enzyme deficiency that allows urates to form in the bladder. Still another type is the oxylate stone. There are other less common kinds of stones.

What causes bladder stones?

There are several factors that can lead to the formation of a stone. If the mineral content of the diet is not right for a particular individual, crystals can form in the urine. These crystals may irritate the bladder wall and cause some bleeding. The crystals combined with blood and mucus from the nidus, or core around which the rest of the stone forms. Bacterial infection may also play a role. Another factor is the pH, or acidity of the urine. Bacterial growth is favored if the urine is alkaline rather than neutral or acidic. These bacteria coupled with crystals that may form in an alkaline environment can lead to a stone. Struvite stones may form in this way. Heredity, diet, and general health may all contribute to the problem.

Does it take long to form a stone?

No, it will depend on how many crystals are present, how bad the bladder infection is, and the pH of the urine. Stones can form in as little as a few weeks. More typically though the problem develops over a few months. .

How do I know if my pet has a stone?

The same symptoms that occur with a bladder infection may occur with bladder stones, specifically, straining to urinate and blood in the urine. Sometimes, if the stones are large enough your veterinarian can feel them through the abdominal wall. However, failure to feel them does not rule them out. Most bladder stones can be seen on an x-ray, or with ultrasound. Some stones may not show up on an x-ray. In those cases they can be seen by placing a die that shows up on x-ray in the bladder. Your veterinarian has the training and equipment to make the diagnosis.

Can bladder stones be treated?

Yes, there are several methods used depending on the type of stone, and the severity of the problem they are causing. The quickest way to resolve the problem is to remove the stones surgically. The veterinary surgeon opens the abdominal cavity, localizes the urinary bladder, opens the bladder and removes the stones. The bladder and urethra are then flushed to remove any sand present. Another option is to dissolve the stones with a special diet. The type of diet depends upon the type of stone. This method avoids surgery but can not be used for all types of stones. A third method is to place a urinary catheter in the bladder and hydropulse, or flush the stones out. This method is only successful if the stones are very small. Once the stones have been removed, your veterinarian can have them analyzed and make recommendations to keep the stones from reoccurring.

How can I prevent my pet from getting bladder stones?

Prevention is always preferable to curing diseases. Your pet should always have plenty of clean, fresh water available. Just as important is the opportunity for your pet to pass urine. Frequent walks allow the animal to urinate and flush bacteria and crystals from the bladder. Your veterinarian may recommend a urinalysis as part of the annual physical your pet receives. This is the best way to detect a problem before it gets out of hand.

by William M. Fraser, D.V.M.

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