Bladder Stones

Bladder stones are just that. Stones that form in the bladder. The stones are made of different things depending on the condition that produced them. Some are made of calcium in the form of calcium oxalate. Others are known as magnesium ammonium phosphate aka triple phosphate aka struvite stones. There are also urate stones and cysteine stones.

When the components that make up the stones are in high enough concentration in the bladder, they will form crystals. Lots of crystals stick together to form sand and that ultimately grows to be a full sized stone.

Calcium oxalate stones usually form because the body is kicking too much calcium out in the urine. There are some breeds more prone to these stones, namely the bichon.

Struvite stones are nearly ALWAYS associated with infection in the dog. Treat the infection, you solve the crystal problem. I've had ONE patient in 11 years that was a true primary struvite producer. They happen, but they're rare. Cats are more capable of producing struvite stones independent of infection.

Some dalmations have a glitch in their metabolism of a particular amino acid and are prone to producing ammonium biurate (urate) crystals.

Out of all of these types of stones, only one can be dissolved once it's formed and that's the struvite. In the case of the struvite you can actually feed a diet designed to acidify the urine and dilute the concentration, and those guys can dissolve. In all other cases, you can't dissolve it and you must go in surgically to remove them. Surgery is fairly straight forward and involves making an abdominal incision and then one into the bladder to remove the stones. That's what the images above come from. Each picture represents a stone or stones taken out of one dog.

More than 95% of stones should be visible on x-ray. Some stones are invisible to the x-ray by can be seen with ultrasound. Stones must also be large enough to see on x-ray. Smaller stones (bb sized) can't be seen in most bigger dogs. They're just too small to see.

In people, the method most frequently used to treat stones is Extracorporeal Shock Wave Lithotripsy or ESWL. This is pretty cool and involves blasting the target organ/stone with shock waves of sound that pulverize the stone into little bits that are passable. This can be done in dogs and cats but is expensive and not practical. Our pets heal much better than we do from surgery. We're wimps.

Prevention depends entirely on the type of stone. Nine times out of ten we have to change diet to help prevent the urine from becoming too concentrated or too rich in the components necessary to produce a stone. In the case of struvites, we may only have to prevent infection. The most important part of prevention is fairly simple. WATER. These patients need to increase their water intake to help dilute the urine. Some foods help with this. Some foods don't.

It may sound like splitting hairs, but bladder stones aren't the same as kidney stones. My understanding is that people are more likely to develop small stones in the kidneys that then must travel down to the bladder and out. They also hurt like hell. Bladder stones are uncommon and nearly always in men.

Kidney stones are much less common for my patients and if they occur, usually stay in the kidney. Bladder stones, however, are very common and can be in any species, any sex.

People often come in and say that their pet has a history of "kidney stones." They almost always mean bladder stones and I have to ask them to clarify. Like I say - it sounds like splitting hairs, but as you see, it really does represent a big difference between human and veterinary medicine. I also will treat a true kidney stone dog or cat differently than I might a bladder stone dog or cat.

One last thing to be said is regarding the difference between males and females in regards to stones. In the female, the shorter, larger diameter urethra can pass lots of smaller stones. Large stones just stay in the bladder. In the male, large stones don't worry me. Little stones do. If they are small enough to leave the bladder, but large enough that they can't make it through the bone that is within the penis, then they can become lodged in place and obstruct the urethra. Now the patient can't pee and it's an emergency. For this reason, I usually won't recommend that we try to dissolve stones in a male dog, even if they are a type that can be dissolved. The last thing I need is that big stone becoming a little stone and then obstructing the patient. Once they are down the urethra, I have to first get them moved back up into the bladder so I can remove them. It was painful the first time as then went DOWN the urethra. Now I have to double the insult by forcing the things back up the poor urethra. Ouch.

AMH