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Calcium Oxalate Stones in Dogs: Diagnosis & Symptoms

Calcium Oxalate Stones in Dogs: Diagnosis & Symptoms

Bladder stones, or uroliths, are rock-like structures of minerals that form in the urinary bladder. One common type of bladder stone in dogs is known as calcium oxalate, which is made up of calcium oxalate crystals. Although calcium oxalate stone formation is complex and not fully understood, experts believe there could be a variety of different causes.

Because bladder stones can be common in dogs, pet owners should become familiar with the symptoms. Recognizing the symptoms early can help lead to a successful diagnosis and treatment.

Symptoms of Bladder Stones in Dogs

Sometimes dogs don't show any clinical signs and bladder stones are discovered by accident through routine testing or tests conducted for an unrelated condition. Most dogs will show signs that are similar to the symptoms of a bladder infection. Symptoms of bladder stones in dogs include:

  • Straining to urinate
  • Blood in the urine
  • Frequent urination without producing much urine
  • Licking around the urinary opening
  • Pain while urinating
  • Urinary accidents

A common sign of bladder stones in dogs is the presence of blood in the urine. This is caused by stones rubbing against the bladder wall, which irritates and damages the surrounding tissues, causing bleeding and discomfort.

Another symptom is that dogs will strain to urinate. This can result for various reasons, including swelling and inflammation of the bladder walls or urethra. Large stones can cause an obstruction within the bladder, while smaller stones may cause an obstruction within the urethra. When an obstruction occurs, dogs are unable to empty their bladder or sometimes urinate at all, which leads them to frequently try to urinate without producing much urine.

Diagnosis of Bladder Stones in Dogs

Because the symptoms of bladder stones in dogs are similar to other diseases, a proper diagnosis is important. Diagnosis often involves an ultrasound or X-ray of the bladder. Most calcium oxalate stones can be seen on radiographs, but in some cases, small stones can be hidden by bones or other body parts.

If your veterinarian suspects your dog has a bladder or kidney stone, he or she may conduct a variety of tests, including:

  • X-rays to help detect the number and size of stones
  • An ultrasound to help verify the location of stones and check for an obstruction
  • A contrast study to help confirm blockage and stones by outlining the stones in the bladder with dye
  • A urinalysis to help determine the acidity of the urine and to check for crystals that may help predict the type of stone

After a stone is found, surgery is often required to remove it and determine the type of stone. When the stone is retrieved, it will have to be analyzed in a laboratory to determine the composition and type.

Sometimes veterinarians may be able to make an educated guess about the stone type, based on radiographic appearance and urinalysis results. If the urinalysis shows the presence of acidic urine and calcium oxalate crystals, a veterinarian may presume that they are calcium oxalate stones.

Treatment and Prevention

Because calcium oxalate stones cannot be dissolved, treatment often involves a costly surgery or techniques to break the stones into smaller pieces that can pass out in the urine.

Unfortunately, there is a high chance of recurrence after dogs develop calcium oxalate stones. In fact, approximately 50% of dogs that have undergone surgery for stones will develop new calcium oxalate stones within three years unless proper prevention is instituted.

Because calcium oxalate stone formation isn't fully understood, preventing calcium oxalate stones in dogs is complex. Prevention is often focused on feeding the dog a therapeutic diet with high-quality ingredients that can help reduce stone formation. It's also important to dilute the urine and ensure a dog's diet is low in the particular compounds that contribute to stone formation. Monitoring for stone recurrence is often necessary for the rest of the dog's life.

How Cal Ox Can Help

Cal Ox from Thomas Labs® is formulated to support urinary tract health in dogs that have had or are predisposed to calcium oxalate stone formation. Cal Ox helps diminish the likelihood of bladder stone formation by minimizing available oxalates, limiting crystallization, and supporting ideal urine pH and flow.

If symptoms are caught early, most cases of bladder stones in dogs can be treated successfully. You should contact your veterinarian right away if you notice any questionable symptoms or if you're concerned that your dog may have bladder stones.


The materials and information provided on this website are not intended to replace the medical advice or services of your veterinarian or other pet healthcare professional. Consult your own veterinarian if you have medical questions concerning diagnosis, treatment, therapy, or medical attention.

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