Bladder Stones in Cats

Mrs. Taylor was feeling very sorry for her cat, Jessica, because the cat seemed to be in discomfort when she tried to urinate.  As I examined Jessica and continued to speak to Mrs. Taylor, she revealed that Jessica had been urinating in a bathroom sink and the urine was bloody.  This was actually the second time that Jessica had been presented at my office for hematuria, blood in the urine.  We had performed a urinalysis on Jessica at her last visit 2 months earlier, and aside from some red blood cells, the test was unremarkable.

Hematuria occurs frequently in cats and can be caused by a variety of causes including stress, trauma, bacterial or viral infections, bladder stones, or for no known reason.  If an owner observes blood in their cat’s urine, it is a good idea to have the animal examined by a veterinarian and a urinalysis performed.  The urinalysis will give the doctor clues as to the possible causes.

It is not common for cats to get recurrent bacterial infections of their bladders, so if a patient has more than one incident of hematuria, a more in depth work-up is recommended.  Jessica had a second urinalysis and a few crystals along with many red blood cells were observed on microscopic examination.  Neither bacteria nor white blood cells were found, and the pH (acid/base status) of the urine was slightly acidic, which is typical for normal cats.  I asked Mrs. Taylor if she could leave Jessica at our office so that further testing could be performed.

I was considering performing an ultrasound on the bladder or taking x-rays of the cat’s bladder.  Plain x-rays can detect some types of bladder stones, but a special x-ray called a pneumocystogram and/or double contrast cystogram is needed to detect other types of stones or irregularities within the lining of the bladder.  Cats usually need to be sedated for the special x-rays to be performed because catheterization of the bladder is needed.  A bladder ultrasound can be performed on most cats without any sedation.  Another test frequently performed with recurrent hematuria is a urine culture.  The culture is more specific than the microscopic exam of the urine for infection.  It allows isolation of specific bacteria and then a sensitivity to different antibiotics can be determined.

We started with an ultrasound of Jessica’s bladder.  It showed the presence of bladder stones.  We took an abdominal x-ray to count the stones and to see if there were stones in her kidneys or ureters.  No other stones were present.

I called Mrs. Taylor to discuss the findings and options for treating bladder stones in cats.  There are two types of commonly found stones in cats—struvite and calcium oxalate.  Feeding a special diet can dissolve struvite, but calcium oxalate stones will not dissolve with diet and require surgical removal.  Based on the urine pH, I suspected the undissolvable calcium oxalate type of stones.

A technique called urohydropropulsion is an option for female cats with very small stones.  This method pushes the stones out without surgery.  The size of Jessica’s stones was too large for this option, and Mrs. Taylor agreed to surgery.  We performed surgery and removed Jessica’s bladder stones later the same day.  The stones were submitted to a laboratory for analysis, so that we would know exactly what we were dealing with and what preventive measures could be used.

Jessica spent the night at the clinic and was discharged the next day.  Her home care consisted of antibiotics, pain reliever, and a special diet designed to help prevent both types of stones pending laboratory results.  She did well post-operatively and when the stone analysis arrived 2 weeks later, my suspicion of calcium oxalate stones was confirmed.

Calcium oxalate stones can recur, so Jessica’s treatment regime consisted of continuing the therapeutic urinary diet, rechecking her urinalysis in one month, and follow up x-rays in 6 months if no other problems occurred.  A grocery store bought special urinary tract diet was discontinued since it potentially triggered the stones.

Not every cat with hematuria has bladder stones, but it is a good idea to have any cat with recurrent signs tested for this problem.  It is amazing when you see an actual bladder stone to imagine how something like it could form within a bladder.  I describe it similar to rock candy—some crystals, bacteria, or mucous form a small core and then other crystals latch on and form the stone.  Many bladder stones in cats are sharp and irregular, so I cannot understand how some cats can do well for weeks to months without showing signs of discomfort.  Bladder stones are especially dangerous to male cats, because small stones can become lodged in the cat’s urethra and create a life threatening urinary blockage.  If you have a male cat, it is important to know that he is urinating daily.

If you have a cat with bladder stones and choose to attempt dissolving them with diet, it can take weeks and follow up x-rays are needed.  If a significant decrease in stone size is not observed within a couple of weeks, surgery should be considered.

Written by Dr. Wexler-Mitchell of The Cat Care Clinic in Orange, CA
Copyright © 2011 The Cat Care Clinic

About Dr. Elaine Wexler-Mitchell

Dr. Elaine Wexler-Mitchell is the owner of The Cat Care Clinic in Orange, CA
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