Struvite, present in the urine of about 40 percent of all healthy dogs, typically causes no trouble unless an infection is present. This compound occurs when ammonium, magnesium and phosphate combine to form crystals in the bladder. Under certain conditions, the crystals bind together to form stones. While not all struvite bladder stones cause problems, in some cases they block the flow of urine and cause life-threatening circumstances.
According to the Mar Vista Animal Medical Center website, dogs don’t form bladder stones unless they are infected with staph or another urease-positive type of bacteria, though exceptions to this rule exist. Some breeds are predisposed to forming struvite stones, including the bichon frise, the dachshund, the Shih Tzu, the Labrador retriever and the miniature schnauzer. Most dogs who end up with struvite stones are female and are less than 3 years old.
Struvite bladder stones are sometimes found by accident when the dog is being examined for completely unrelated difficulties, especially since the stones show up clearly on X-rays. Stones are likely in a dog who passes bloody urine or strains to pass any urine at all. A dog who continues to have bladder infections, particularly if they're caused by staphylococcus, may also suffer from stones. Since struvite isn’t the only substance that can form bladder stones, your dog’s veterinarian will have to confirm struvite before a treatment regimen can begin.
Many times struvite stones are treatable by feeding a special diet for three to four months. Since the dissolving stones will continually release bacteria, the dog will also need antibiotics. Cytoscopic removal -- taking the stones out through the urinary tract without making an incision – is an option for stones that are small enough. In some cases a veterinarian may be able to remove small stones by filling the bladder and forcefully pushing the urine and the stones out together. Large stones typically require surgical removal.
Dogs who are predisposed to forming struvite stones are likely to get them again unless preventive measures are put in place. Your vet may recommend that you feed your dog a special diet that is lower in magnesium, phosphorous and protein. This is a different diet than the prescription food used to dissolve stones. Medication to keep his urine acidic, discouraging formation of the stones, is part of treatment. Your vet will check your dog several times per year to make sure the struvite stones haven’t come back.