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Bladder
StonesIntroduction
Bladder stones in a cat are rather common and often are derived from fine, granular struvite crystals. A cat with bladder stones tends to have the classical symptoms of feline lower urinary tract disease: straining to urinate, bloody urine, urinating in unusual places, genital licking. In the course of testing to pursue these symptoms, a radiograph is taken and a stone or group of stones is seen in the urinary bladder.
Struvite stones
Urinary tract infections are a very uncomfortable problem for humans and animals alike. In pets, especially cats, urinary tract infections can sometimes be accompanied by bladder stones, which can both initiate and promote infection in the bladder.
While dogs do get urinary tract infections, cats are much more susceptible. Female cats are also more susceptible than male cats. This may be because the urethra (opening from the bladder to the outside world) is very short in female cats, and it is close to the rectum, where there is a large amount of bacteria. In addition, cats do more grooming than dogs, which can spread bacteria.
Dogs are usually housebroken, and because they go outside, there is more opportunity for an owner to notice when there is a problem. The owner may notice straining or blood in the urine sooner. Infections often go unnoticed in cats because the owner may not see the cat using the litter box. Often, cat owners don't notice there is a problem until their pet stops using the box. While some cats stop using the litter box for behavioral reasons, it is important to rule out a medical problem before assuming that the cause is behavioral.
Causes
Since urinary tract infections can be caused by a multitude of factors, it is often difficult to discover the cause. The origin of an infection could be as simple as an overgrowth of bacteria or as complicated as bladder stones.
The formation of a bladder stone is very much like the formation of a pearl inside an oyster. It often forms from a single irritating particle called a nidus, which consists of a tiny particle such as small bacteria. Minerals are deposited on its surface, and over time it grows larger and can become very irritating to the lining of the bladder.
In female cats, these stones can cause recurrent infections with signs such as straining and blood in the urine. Infections caused by bladder stones often respond to antibiotics but return once the antibiotics are discontinued. In male cats, stones can cause infection and, if a bladder stone becomes lodged in the urethra, make the cat unable to urinate. Such an obstruction can result in the accumulation of urine in the bladder, which can cause the bladder to rupture, a medical emergency that is fatal if untreated.
If bladder stones are suspected, it is a good idea to take X-rays and do an ultrasound examination. Some stones can be seen on a regular X-ray, while others require ultrasound in order to see them. Ultrasound can also identify the presence of sandy residue and thickening of the bladder wall, both of which are signs of possible bladder stone formation.
Because there are several kinds of bladder stones, it is important to find out what kind of stone an animal has before starting treatment. Some stones can be dissolved with medication and others, such as calcium oxalate stones, cannot.
Struvite stones
Treatment
The only treatment for some stones is surgical removal. Surgically removed stones should be analyzed so a plan can be made to avoid the recurrence of stones in the future.
A very good choice for some cats (and some stones) is to dissolve the stone with a special diet. This avoids surgery. It is not successful for all trypes of stones, it is slow (it may take several weeks or a few monyhs to dissolve a large stone, and not all cats will eat the special diet).
Prevention
Prevention is possible in may cases and may include a change in diet, medication, and prevention of bacterial infections that can lead to the formation of stones. Chronic problems with stones and bladder infections that do not respond to standard treatments may require a consultation with a surgeon or specialist. . There are at least four types of bladder stones, based on their chemical composition. If stones are removed surgically or if some small ones pass in the urine, they should be analyzed for their chemical composition. This will permits veterinarians to determine if a special diet will be helpful in preventing recurrence. If a bacterial infection causes stone formation, it is recommended that periodically urinalyses and urine-cultures be performed to determine when antibiotics should be given.
If you have any questions regarding urinary tract infections or bladder stones, please contact your local veterinarian.
