Bladder Stones

Dear Dr. Jody:  Our eight year old miniature schnauzer, “Pogo”, is recovering from bladder stone surgery she had at the emergency clinic two weeks ago.  How did she get these stones, and how do I keep them from coming back?

Bladder stones, also called uroliths, are mineral concretions that form in the urinary tract when minerals dissolved in the urine precipitate out of solution and coalesce.  Stones can form and lodge anywhere along the urinary tract, from the kidneys to the ureters to the bladder to the urethra.  The most common location for a urinary tract stone is the bladder. 

Bladder stones come in a wide variety of shapes and sizes (I once removed the equivalent of five golf balls’ worth of bladder stones from a shih-tzu), and can be made from many different types of minerals.  The mineral makeup of the stone is heavily affected by the dog’s diet, age, breed, and sometimes gender.  Breeds such as the Yorkshire terrier, miniature schnauzer, bichon frise, shih-tzu, and dalmatian are especially stone-prone. 

Many dogs that have bladder stones will develop blood in the urine or an increased frequency of urination.  They may start having accidents in the house or may even be suddenly unable to urinate.  In order to determine whether your dog has a bladder stone, diagnostic imaging such as an abdominal x-ray or ultrasound must be performed.  Your veterinarian will also require a sample of urine to evaluate urine pH, concentration, and to look for concurrent infections.  This information will help your veterinarian determine what caused the stone, and how to prevent its recurrence following surgical removal.

In some cases, bladder stones can be “dissolved” over several months with aggressive dietary manipulation.  Although this sounds simple and straightforward, there are a few potential snags to dietary dissolution of bladder stones.  Firstly, not all minerals are “dissolvable”.  Even if your veterinarian believes the x-rays show a nice smooth dissolvable struvite stone, the stone’s core may actually be made of spiky calcium oxalate, which does not dissolve.  This means that your dog will eventually require surgery to remove the core of the stone.  Additionally, if the stone dissolves down to just the right size for your dog to attempt to pass it in his urine and the stone becomes lodged in the urethra on the way out, you now have a life-threatening situation on your hands.  You will be faced with an emergency surgery, which of course will happen on a statutory holiday when your regular veterinary clinic is closed.  For these reasons, most bladder stones are surgically removed as soon they are confirmed.

Following removal, your veterinarian will send the stone to the University of Guelph for analysis.  The information gained from this test as well as the urine test will help your veterinarian choose the appropriate long term diet to prevent recurrence.  Most stone diets are designed to adjust the urine pH and concentration in ways that make it difficult for stones to develop.  Frequent follow-up urine tests for the first year after surgery will ensure that the diet is achieving the desired effect. 

Please consult your veterinarian immediately if you suspect your dog may have bladder stones.  It hurts to have annoying little rocks rolling around inside your bladder.