What to Know About Bladder and Kidney Stones in Dogs

Medically Reviewed by Amy Flowers, DVM on December 05, 2021
4 min read

Metabolic kidney stones are the stones that are formed due to an imbalance in the blood or urine. They are more common in dogs as compared to the stones caused due to infection. Kidney stones are more common in female dogs than in male dogs. 

Kidney stones in dogs are common, especially in toy breeds and small terriers. Some affected breeds include the bichon frise, miniature poodle, Maltese, Chihuahua, Lhasa apso, Pom­eranian, Yorkshire terrier, and Cairn terrier.

In some dogs, bladder and kidney stones may become serious in just two days. In others, it may take two months before serious medical attention is required. 

Calcium oxalate, urate, and struvite are the most common types of stones in dogs. Of these, only struvite stones are a result of an infection in dogs. 

Other stones are caused by high blood calcium levels, liver disease, or other conditions. Sometimes, a nutrient imbalance may also cause stones in dogs. Some dogs and cats inherit genetic conditions from their parents that make them more prone to having stones. 

One past study showed that calcium oxalate accounted for 41.3% of all stone formations in dogs. The other compositions, in order of their prevalence, are: 

  • Struvite 
  • Compound 
  • Urate
  • Mixed 
  • Cystine 

Struvite stones are more common in female dogs because they are more likely to develop urinary tract infections. Urate stones are commonly found in dalmatians. Other dogs are relatively protected from these stones because their bodies can convert uric acid to allantoin. 

Allantoin dissolves easily in the urine compared to uric acid. Because this conversion takes place in the hepatocytes, cells of the liver, a disease affecting the liver, such as hepatic failure, can lead to the formation of urate stones in dogs. 

The sequence of events leading to stone formation is not fully understood. But researchers expect that a high intake of protein and minerals in a dog’s diet may contribute to an increased concentration of salts in the urine. 

Some bacterial infections of the urinary tract may also increase the concentration of salt in the urine. Many factors can lead to the formation of stones in dogs, including: 

  • High salt concentration in urine 
  • Decrease in the natural inhibitors in the body that prevent crystal formation 
  • pH levels that favor the formation of salt crystals 
  • Salt retention for an extended period in the urinary tract 

Most urinary stones in dogs are located in the urethra and the urinary bladder. There are only a few stones in the ureters and the kidneys. The symptoms differ based on the stones' location. Some common signs are blood in the urine, abdominal discomfort, urinary accidents, urination in small amounts, and difficulty urinating. Stones in the kidneys and the urinary bladder can also block the flow of urine. 

If your dog shows these symptoms, you should consult with a vet immediately because any obstruction in the urinary tract can be harmful. 

Your vet will recommend an evaluation of your dog's urine and blood for diagnosis. The most common methods for screening the urinary tract are ultrasound and X-rays.

Most stones tend to show on the X-rays. But if the stones are not visible, a gas or contrast agent may be introduced into your dog's urinary tract. This allows the stones to show up in the imaging test. 

The vet may also use a fluoroscopy to diagnose urinary stones. This is an imaging test in which an X-ray beam passes through your dog’s body and creates an image. The image is then displayed on a monitor. Your vet can then see the internal organs' movement in real time to make a diagnosis. 

Bladder and kidney stones in dogs are usually surgically removed. Sometimes they are treated with interventional radiology, which is the technique used for stones in people. Your vet will use a scope to see the stone. Then they will direct a laser fiber onto the kidney stone through a cystoscopy. 

When the laser touches the stone, its energy breaks the stone into small pieces. In more than 90% of the cases, dogs can pass the smaller fragments of the stones. 

Most dogs can go home on the same day as the treatment. 

Some other interventional techniques to break down urinary stones are percutaneous nephrolithotomy and urethral stenting. 

Urinary stones can be harmful to your pet's health. If you notice any symptoms of a urinary obstruction, call your vet.