Bladder Sediment And Stones - Crystals And Uroliths - Urolithiasis
Pets of any age or breed can produce mineral sediment, called "crystals" or mineral stones, called "uroliths" in any part of the urinary tract. They usually develop in the bladder and pass down into the urethra. (Kidney stones are rarer in dogs and cats than in people.) The most common stone, struvite, usually occurs as a consequence of lower urinary tract infection. Other stones develop for different reasons (see below) While some pets with bladder stones show no clinical signs, others behave as pets do with lower urinary tract pain. A stone can lodge behind the bone in a dog’s penis (the os penis), completely blocking the urethra. Stones and associated mucus can plug a male cat’s urethra. This causes considerable straining, no urine and dramatically increasing pain leading to shock as the bladder increases in size.
A diagnosis is made by examining urine sediment, x-ray and ultrasound. FINDING A FEW CRYSTALS IN URINE IS NOT ON ITS OWN OF ANY SIGNIFICANCE. CRYSTALS ARE ONLY SIGNIFICANT IF THERE IS ASSOCIATED DISEASE OR A HISTORY OF PREVIOUS DISEASE. EQUALLY, FINDING NO CRYSTALS IN SEDIMENT DOES NOT ELIMINATE UROLITHIASIS. A SOLID BLADDER OR URETHRAL STONE MAY BE SHEDDING NO CRYSTALS.
The largest stones can actually be felt on abdominal palpation while others are revealed by plain or contrast x-ray or ultrasound. Treatment varies according to the type of stone but always involves eliminating the underlying cause such as bladder infection and reducing the quantity of sediment or preventing its recurrence though diet management. Large stones or those causing urethral blockages are surgically removed.
Types Of Bladder And Urethral Stones And Their Treatment
Technically, these are made of magnesium ammonium phosphate, sometimes called triple phosphate, most frequently called struvite. This is the most common canine bladder and urethra stone usually triggered by Staphylococcal or Proteus bladder or urethra infection. These bacteria create alkaline urine, the ideal environment for struvite to form in. Persistent and efficient antibiotic treatment is vital. Several commercial diets promote acid urine and Ashley McManus can advise you on which are best for your pet. Given time (on average three months) small struvite uroliths will dissolve in pets fed these diets. They are designed for short-term use only. Large stones are surgically removed. Pets that suffer from recurring urinary tract infection are very likely to develop more struvite uroliths. Sometimes permanent prophylactic antibiotic therapy is the practical treatment of choice.
Calcium Oxalate Stones
These are the second most common bladder and urethra stones in pets. They cannot be dissolved by dietary means and if too large to pass through the urethra, require surgical removal. Urinary acidifying diets, the preferred treatment for struvite stones, may actually promote growth of calcium oxalate stones. Pets with these stones should be encouraged to drink more water. The simplest way to do this with pets that eat dry food is to switch them over to wet food diets. To control calcium oxalate stones feed a diet with reduced protein, calcium and sodium and that promotes acid urine. Avoid excess vitamin D or ascorbic acid that predisposes to these uroliths. For dogs, avoid chocolate which contains oxalates. (Asparagus contains asparagine which is said to break up oxalate crystals.) Fortify the diet with vitamin B6, vitamin K, vitamin A and the amino acid lysine.
We see these stones most frequently in male Dachshunds. Bulldogss are also reported to suffer from them. A very low protein diet, supplemented with a little sodium bicarbonate to boost the urine pH just above neutral is the recommended treatment.
Uniquely, the Dalmatian can suffer from urate stones. These stones rarely occur in other breeds. The objective of treatment is to maintain a neutral urine pH and restrict dietary purine and sodium.