Urinary Stones In Cats: Symptoms, Diagnosis And Therapy

The purification of the blood takes place in the kidneys. The kidneys filter metabolic waste products from the blood and produce urine, which is designed to help remove such waste products from the body. Blood salts also pass into the urine. When these salts in urine exceed a certain concentration, they can precipitate out in the form of urinary crystals and even cake together to form solid urinary stones. A chemical analysis of urinary stones can be used to determine their composition. In most cases, there are two types of urinary stones in cats: struvite (magnesium ammonium phosphate salts) or calcium stones. Urinary stones can occur in all cat breeds. Middle-aged cats are usually first affected.

Symptoms

A stone bearer’s discomfort depends on where the stones are located. You can find urinary stones in the renal pelvis, in the ureter, in the urinary bladder, or in the urethra, i.e. in all urinary tracts. Urinary stones are sometimes an incidental finding when they are in a location where they do not interfere with urinary flow. On the other hand, urinary stones can impede or completely block the outflow of urine. If this happens in the renal pelvis or in the ureter, the symptoms can be very unspecific. Discomfort, lack of appetite, less desire to exercise, lack of play instinct and weight loss are then sometimes the only complaints and accordingly difficult to interpret. Bladder stones, on the other hand, lead to an increased urge to urinate (stranguria), frequent passing of small amounts (pollakisuria), or bloody urine (hematuria). If a urinary stone gets stuck in the renal pelvis, in the ureter, or in the urethra, it can cause considerable pain. If this completely blocks the passage of urine, there is a risk of kidney failure.

Diagnosis

The diagnosis of urinary stones is based on the X-ray examination and the ultrasound examination. In the case of special questions, urinary stones can also be detected in computed tomography.

Therapy

• Basically, urinary stones should be removed. How much time is available for this depends in turn on how high the stone load is and what symptoms the stones cause.
• In the case of struvite stones, which cause a little discomfort, you may have enough time to dissolve the stones by changing your diet over 3-6 weeks.
• Stone removal is advisable for bladder stones associated with a severe bladder infection (cystitis). In queens, cystoscopy can be used to break up the bladder stones with laser light and remove the debris through the urethra.
• In cats, there is no possibility of cystoscopy to remove the stone due to the delicate urethra. In cats, the urinary bladder is therefore opened via an abdominal incision in order to remove the bladder stones.
• Bladder stones that block the ureter can be surgically removed in all cats. Rarely is there a chance that a ureteral stone will cross over into the urinary bladder as a result of medication and thereby release the ureter.
• Kidney stones are usually calcium stones, the formation of which can hardly be influenced by feeding and which often occur in groups at the same time. Kidney stones that cause symptoms should also be treated in order to guarantee the patient a good quality of life.
• Individual kidney stones can be removed through kidney surgery. For this purpose, the renal pelvis is opened with the finest instruments under the surgical microscope and the kidney stone is removed with a tiny stone basket. Alternatively, a kidney stone can be removed by examining the kidney pelvis (pyeloscopy). If there are several kidney stones, it is important to ensure permanent urine drainage. For this purpose, a tube (stent) is inserted into the ureter that connects the renal pelvis to the urinary bladder. Before doing so, it must be checked whether the affected kidney has already been damaged to such an extent that it can only be removed.

Forecast

The prognosis depends crucially on the stone load, i.e. on how many stones are present, where they are, how long the symptoms have existed, and whether there is any previous damage to the kidneys. The prognosis for bladder stones is good to very good. The urinary bladder has a very good potential for regeneration, and accompanying infections can usually be controlled with appropriate treatment. Individual kidney and ureteral stones can usually be removed easily without leaving permanent damage. Cats with recurring calcium stones in the kidneys are high-risk patients for whom the experienced urologist can decide on a case-by-case basis which treatment measures are appropriate in order to achieve lasting relief.