A bladder stone, or urolith, develops when mineral salts present in urine combine and harden. Most stones occur in the bladder and urethra, but occasionally stones form in the kidneys and ureters, the tubes that carry urine from the kidneys to the bladder. Dogs may develop one or multiple large or small stones. The five main types that affect dogs are struvite, calcium oxalate, urate, cystine, and silicate.
Risk factors and detection
Bladder stones affect dogs of any age and breed, but certain stones tend to affect specific breeds.
- Struvite stones affect miniature schnauzers, dachshunds, poodles, Scottish terriers, Welsh corgis, beagles, and Pekingese.
- Calcium oxalate stones affect miniature schnauzers, miniature poodles, bichons frises, Yorkshire terriers, Lhasa apsos and Shih Tzus.
- Urate stones affect Dalmatians, English bulldogs, Yorkshire terriers, and miniature schnauzers.
- Cystine stones affect dachshunds, English bulldogs andNewfoundlands.
- Silicate stones affect male German shepherds and Labrador and golden retrievers.
Female dogs with urinary tract infections can develop struvite stones. Other risk factors include medications or metabolic diseases that cause increased mineral-salt concentrations in the urine. Urine retention and anatomic abnormalities of the bladder also could contribute to bladder stone formation.
Signs of a bladder stone can include:
- vocalizing during urination
- painful urination
- bloody urine
- frequent attempts to urinate
- straining to urinate
- dribbling when urinating
- lethargy
- appetite loss
- inability to urinate.
These last three signs may indicate a bladder stone is completely obstructing urine flow. This condition is life-threatening, so take your dog to the veterinarian immediately.
Your veterinarian will perform a complete physical examination and may use blood tests, X-rays, ultrasound, urinalysis, bacterial culture and sensitivity testing, and stone analysis to diagnose the presence and type of bladder stone, as well as any underlying metabolic disease. If your dog passes a stone while urinating, save it. Your veterinarian will have its mineral content analyzed before choosing a treatment.
Prevention and treatment
Fresh water, a clean litterbox, frequent bathroom breaks, and avoiding obesity reduces your dog's risk of bladder stone development. If your dog develops a urinary tract infection, seek veterinary care and complete all antibiotic treatments.
When treating bladder stones, your veterinarian's goals are to relieve any urinary obstruction, treat any infection, and dissolve or remove the stones. To remove a blockage, your veterinarian may use a urinary catheter or a cystoscope, a special scope designed for evaluating the bladder. Other treatments include surgery or urohydropropulsion, in which your veterinarian uses a catheter and fluid to flush out the stone. If the obstruction causes other illness, such as metabolic abnormalities, your dog may need intravenous fluids and hospitalization.
The different types of bladder stones require different treatments. Struvite, urate, and cystine stones respond well to medical dissolution. Depending on the type of stone, your veterinarian may use a special diet and possibly drugs to dissolve it. The goals of this treatment are to decrease the concentration of stone-forming salts in the urine, increase the solubility of those salts by altering the urine's pH, and increase urine volume.
Calcium oxalate and silicate stones are harder to treat and often require surgery. Your dog also may need surgery to relieve an obstruction, to remove stones that don't respond to medical dissolution, or to correct anatomic abnormalities of the bladder that could contribute to stone formation. Veterinarians prefer surgery when medical dissolution is inadvisable because of other medical conditions.
Prognosis
Dissolving bladder stones with a special diet can take a few weeks to a few months. During this time, don't vary your dog's diet or treatment will be ineffective. Your dog will need follow-up urinalyses, bacterial cultures, and X-rays to ensure complete dissolution. Bladder stones are more likely to recur in dogs with metabolic disorders or a hereditary predisposition. But in many cases, special diets and medications that alter urine acidity can prevent recurrence.
Dogs who undergo surgery generally recover without problems, but they also will require preventive care to halt recurrence.
