03/12/2023
Bladder Stones
The kidneys remove various substances from the blood so they can be excreted from the body in the urine. These are substances which would poison us if left to accumulate. Many of them are electrolytes (charged elements or compounds dissolved in the water which makes up most of the urine).
Bladder stones are more likely to form where the concentration of some of the excreted substances is unusually high, where the urine is way too acidic or alkaline, or where infection or other trauma leaves debris in the urine which assists crystals to form. The crystals can then coalesce into stones.
So, urine which is too alkaline or too acidic can form stones. Stones can lead to infection. Infection can lead to alkaline urine, causing the most common stone.
A couple of hundred years ago sailors were prone to bladder stones. Because their water supplies were often very low or of very poor quality they did not drink enough water. To conserve body fluid, their urine was chronically highly concentrated. Matthew Flinders suffered from bladder stones from his early twenties. He was unusual in that he worked out his stones had formed in alkaline urine, so they were likely to dissolve in acidic urine. He achieved this by drinking lots of vinegar. A monk in the thirteenth century with bladder stones designed a metal rod with a sharp tip, which he poked up through his p***s into his bladder. He would then position the tip of the rod against a stone and hit it with a hammer. For the next few days he would be in agony as he passed the small, jagged pieces of stone, then he would repeat the exercise. It only took him eighteen months to get rid of them all. Apparently he consoled himself with the prospect that earthly suffering increased one’s chances of a place in heaven. Sadly he never patented the technique.
The following narrative applies mostly to dogs. The story in cats is quite different.
The first thing a Vet will do when bladder stones are encountered is to check the pH of the urine and look under the microscope for crystals. These steps can help to identify the composition of the stone(s) and help avoid their recurrence once removed. Radiographs (Xrays) are useful in most cases to see how many stones there are and if any small ones are down along the urethra (which must be removed). Some Vets will use additional imaging such as ultrasound or MRI because some stones will not show up on Xrays.
Most will then proceed to surgery. This will be urgent if the urethra is blocked. Mammals start to die within a few days of being unable to pass urine. The surgery is almost always simple and free of complications if urine is still able to be passed.
The first picture is of a jar full of stones I removed from a Lhasa Apso dog in 1987. The dog weighed about 4 Kg. Unfortunately much of the collection has dissolved to form the layer in the bottom of the jar. My nurse always said if the dog had gone for a swim it would have sunk! It came in for a sore eye, and I felt the stones during a pre-anaesthetic health check. I felt them rub together and when the dog passed a few drops of urine the owner commented that it was always doing that. A few changes to the diet were made, and the dog was encouraged to drink a lot more water. The stones did not recur.
The next picture is of a stone from a dog presented because its urine was obviously bloody. There was only one stone present. This stone was of the type normally found in alkaline urine however this dog’s urine was mildly acidic. So to prevent recurrence the dog’s urine was kept a bit more acidic with tablets and the dog was induced to drink more water. Its urine is monitored for blood, and to keep the urine at the right pH by adjusting the dose of medication.
The last one was a single stone removed from a Dalmation. Dalmations are unusual in that they can have very high levels of uric acid in their urine. This is the compound that causes gout. This dog was placed on allopurinol to help with uric acid excretion. It needed close monitoring, as the stones can quickly form again, and can form in the kidneys. The kidneys were Xrayed and no stones were seen. I have once removed a kidney which had ruptured in a Dalmation due to urate stones forming after commencing allopurinol. This was in 1988, and more advanced imaging was not readily available. The owners moved away about a year later and I was unable to follow up.
So, SIGNS OF BLADDER STONES include blood in the urine, constant straining while only passing a small amount of urine, or no urine at all where a complete blockage is present, abdominal pain, or a hard palpable lump in the abdomen, where sometimes two or more stones can be felt to grind against each other. All these symptoms can also be caused by other diseases.
Remember my posts are not to assist people through the diagnostic minefield, only your Vet can diagnose the problem. And please remember to phone the Vet before you head there, they need to be able to prepare for an emergency or advise you to go elsewhere.
