Sunday, July 11, 2010

These Stones Aren't Rolling

It was Christmas eve day 2006. With the families coming for dinner & present opening in a few hours, I was preoccupied with cleaning and cooking so didn't notice that Marta didn't leave her sleeping spot under the covers even when we got up, or that she was quieter than usual. Late that afternoon Bill came to me with the words I hate to hear..."I don't think Marta feels good."

Just as I do every day for my patients, I did a physical exam on Marta. Subdued but responsive, hydration ok, coat & skin ok, ears/eyes/nose/throat ok, teeth & gums ok, heart & lungs ok, kidneys ok, intestines ok, bladder... Bladder not ok. Marta's urinary bladder was moderate sized & very firm. She was noticeably uncomfortable as I palpated this area. Feeling a firm bladder was not unknown to me, it was the classic feeling of a male cat with a urinary obstruction. But wait, Marta was a female, females don't obstruct!

Never having seen or even heard of and obstructed female cat, I treated Marta for urethral spasms, hoping that in a few hours she would be back to herself. As with most of my male patients with a urinary obstruction rather than merely spasms, there was no improvement. I knew she had to be worked up. With our clinic closed for Christmas, this meant a trip to the Emergency Clinic. As the families arrived, I headed out with Marta, telling everyone to start without me.

The Dr. at the Emergency Clinic came to the same felt like an obstruction. Marta's urinalysis showed no cystals, her x-rays showed no signs of stones, yet she was blocked. An ultrasound of her bladder showed what might be a mass but wasn't conclusive. She would need more tests later that night, but what she needed right away was a catheter to allow the urine to leave her bladder. It had been many years since I had catheterized a female cat, but that was more experience than the Emergency Clinic Dr. had, so I was chosen to do this. With the catheter in place and Marta awake, I returned home to Christmas dinner and presents, but all the while worried about Marta. Like I have written in an earlier post, I wondered, is this "it"? Has her Feline Leukemia become active, is this lymphoma? Or was this the more typical bladder tumor, transitional cell carcinoma ? Neither were good.

A late night call from the Emergency Clinic was my best present that evening. Marta's blood tests were normal, and the special x-ray studies showed that the blockage was not a tumor, it was a stone. This wasn't "it", this was curable and surgery would be performed as soon as the emergency schedule would allow.

The next call I received came in the early hours of Christmas day, the surgery was a success and Marta was recovering well. Just like the spirits in Charles Dickens' "A Christmas Carol" the Emergency Clinic had done it in one night.

On Christmas day, Bill and I drove to the Emergency Clinic to receive yet another present, Marta. She has not had a repeat of her urinary stone, which was confirmed as urate, the type that occurs only 6% of the time, which isn't seen readily on x-rays, and which I've diagnosed at most 1/2 a dozen times since I've been in practice. And in 20 years of practice, she remains the only blocked female cat I know of.

Bladder stones, also known as uroliths or cystic calculi occur when minerals in your cat's urine crystalize, mix with organic material (usually mucus-like) and form stone-like masses in it's bladder.

Cats can have several types of bladder stones. The two most common types are struvite (magnesium ammonium phosphate or "triple phosphate") and calcium oxalate, account for approximately 90% of all cat bladder stones and are found in both male and female cats. Age and diet play important roles in the formation of these stones. Struvites form in neutral or alkaline(high pH) urine and are more commonly seen in younger cats; while Calcium oxalate stones form in acidic (low pH) urine, and are more commonly seen as age increase. In the past, the most common type was struvite, but over the years, the number of calcium oxalate uroliths has increased. Now, the two types occur with almost equal frequency.

Less commonly seen are Urate stones, which account for approximately 6% of bladder stones.

Stones can be present without causing any symptoms, but more often, they are associated with hematuria (blood in the urine), pollakuria (increased frequency of urination) and dysuria (difficulty passing urine). Many cats with bladder stones will urinate outside of their litterbox. While most stones remain in the bladder, some stones may pass into the urethra (the tube leading from the bladder to outside the body). Because the male cats urethra is much narrower than the female, a stone is more likely to cause partial or total obstruction so that little or no urine can pass. Obstructions are painful and often are life-threatening emergencies. Other bladder problems such as urinary crystals (without stone formation), infection, tumor or an inflammatory condition such as Interstitial Cystitis; or non-bladder problems, such constipation, may result in similar symptoms, so it is important to have your cat evaluated.

While urinalysis is helpful to determine if a urinary problem is present, but is often not enough to diagnose a bladder stone.

Many stones can be detected by x-rays, however, some (urate stones) don't show up well or may be too small to be seen. In these cases, a bladder ultrasound is the best method of detection. When ultrasound is not available, special x-rays involving instilling a contrast agent into the bladder in order to see the stone more clearly can be done.

Management of stones depends on the numbers, size & type of stone; as well as the cats condition.

In cases where struvite stones are suspected, or an owner wishes medical management of their non-obstructed cat first, the cat is fed a stone-dissolving diet and x-ays and urinalysis are monitored for response to treatment. This may take several weeks, and the cat may be at risk for becoming obstructed. Oxalate and urate stones will not dissolve with diet.

Small stones that are not causing blockage may be removed in a flushing procedure called voiding urohydropulsion. Any stone(s) flushed from the bladder can be sent to a laboratory for evaluation to determine the type of stone.

If there is an obstruction, immediate emergency treatment to relieve the obstruction is required. Obstructed cats are often dehydrated, have electrolyte and acid-base imbalances, and increased levels of waste products in their bloodstream. These problems can lead to heart and kidney problems as well as bladder damage, and even death if left untreated. Just as with Marta, the urethra is catheterized to restore flow of urine and fluid therapy is started. Blood and urine tests are done to determine the cat’s status and guide further treatment

Surgery is needed if the cat continues to re-obstruct. Also, removing the stones allows for faster resolution of the stone(s) and pain. As with hydropulsion, the stone(s) recovered can be analyzed.

Antibiotics are prescribed if a bacterial infection was part of the problem (which is uncommon) or if the cat was catheterized to relieve an obstruction.

Cats that have had crystals or stone are at risk to develop them again. Fortunately, most cystals & stones can be prevented by dietary management. Struvite management diets typically help to produce an acidified urine, while calcium oxalate management diets produce a slightly alkaline urine. The Cat Care Clinic carries commercially prepared diets to help treat and prevent urinary crystals and stones.

Double clicking on photos will enlarge them.

These stones have very sharp edges

This stone is smooth and rounded

This is an ultrasound of a bladder stone

This stone was not seen on x-rays. It shows up on the double contrast study like a photographic negative. It is the dark area in the center of the bladder, it is surrounded by the dye which appears white around it.

These small stones were flushed out by voiding urohydropulsion

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