Bladder stones in dogs

Content by Emma Chandley BVetMed PGCertSAS MRCVS 

Bladder stones, also known as uroliths or cystic calculi, are hard mineral deposits that form within the urinary bladder. They can vary quite a bit in size, number and composition. Some dogs develop a single larger stone, while others may have many smaller stones sitting in the bladder at the same time. In some cases, stones can also become lodged in the urethra or other locations in the urinary tract. 

These stones can irritate the bladder lining and interfere with normal urination. In some cases, they may partially or completely block the flow of urine, particularly in male dogs. A urinary blockage is considered an emergency and requires immediate veterinary attention.

Several different minerals can form bladder stones. The most common types seen in dogs are struvite and calcium oxalate stones, although urate and cystine stones are also recognised. The underlying cause can vary depending on the type of stone present.

• Bladder stones are mineral deposits that form inside the bladder
• Common signs include blood in the urine and straining to urinate
• Some stones can be dissolved medically, while others require surgery
• Male dogs are at higher risk of dangerous urinary blockage
• Recurrence can occur, so long-term monitoring is often important

Bladder stones develop when minerals within the urine begin to crystallise and gradually stick together over time. Normally, urine contains substances that help prevent this process, but certain conditions can allow crystals to form more easily. The exact cause depends partly on the type of stone involved.

Struvite stones are commonly associated with urinary tract infections, particularly infections caused by bacteria that alter urine pH. These stones are seen more frequently in female dogs because urinary infections are generally more common in females.

Calcium oxalate stones are not usually linked to infection. They’re thought to develop due to a combination of genetics, diet, urine concentration and metabolic factors.

Other contributing factors can include:

• Low water intake
• Concentrated urine
• Dietary influences
• Underlying liver disease
• Certain inherited conditions
• Urinary tract abnormalities

Some dogs may also have repeated urinary infections or chronic inflammation within the bladder, which can increase the risk of stone formation.

Certain breeds appear to have a higher risk of developing bladder stones – although bladder stones can develop in any dog. Factors such as age, sex, diet and underlying health conditions also play a role. 

Breeds commonly affected by calcium oxalate stones include:

• Miniature Schnauzers
• Bichon Frises
• Shih Tzus
• Yorkshire Terriers
• Lhasa Apsos 

Dalmatians are particularly predisposed to urate stones due to an inherited abnormality affecting uric acid metabolism. English Bulldogs and some other breeds can develop cystine stones linked to inherited amino acid transport abnormalities.

The signs of bladder stones can vary depending on the size, number and location of the stones.

Common symptoms include:

• Straining to urinate
• Passing small amounts of urine more frequently than usual
• Blood present in the urine
• Pain or discomfort when urinating
• Urinating indoors unexpectedly
• Excessive licking around the genital area
• Recurrent urinary tract infections

Some dogs may seem unsettled or uncomfortable after urinating. Others develop only mild signs initially, particularly if the stones are small.

If a stone moves into the urethra and blocks urine flow, signs can become much more severe. A blocked dog may strain repeatedly without producing urine, become distressed, vomit or collapse. Complete urinary obstruction is a medical emergency that requires immediate veterinary attention. 

Diagnosis

Diagnosis of bladder stones usually involves a combination of history, a thorough physical examination and urine testing. Your vet may detect discomfort when palpating your dog’s abdomen and urine samples often reveal blood, crystals or evidence of infection.

Imaging is important for confirming the presence of stones. X-rays can identify many types of bladder stones, while ultrasound is useful for assessing the bladder wall and detecting stones that may not show clearly on radiographs.

In some cases, additional tests are recommended to help determine the type of stone present and identify any underlying causes.

Treatment depends on the type of stone, the severity of signs and whether any urinary obstruction is present. Some struvite stones can be dissolved using specially formulated prescription diets combined with appropriate antibiotics if infection is present. Dissolution can take several weeks to months and requires close monitoring.

Many other stones cannot be dissolved and need physical removal instead. Surgery to remove bladder stones is called a cystotomy and this is one of the most common treatment options. Less invasive procedures may sometimes be available in referral settings depending on stone size and location.

Supportive treatment may include:

• Pain relief
• Antibiotics where appropriate
• Increasing water intake
• Dietary management
• Treatment of underlying conditions

Long-term management often focuses on reducing the risk of stones returning. This often involves prescription diets, encouraging good hydration and regular monitoring of urine samples.

Prognosis

The prognosis for bladder stones is usually very good when diagnosed and treated quickly. Most dogs do very well once the stones have been removed, whether that involves surgery or dietary dissolution. Some stone types do have a tendency to recur though, particularly if there is an underlying predisposition, so ongoing monitoring is often advised.

Dogs that develop urinary obstruction can become very ill very quickly if treatment is delayed. Prompt intervention generally improves outcomes significantly.

“One of the more challenging aspects of bladder stones is that the early signs can look very similar to a simple urinary tract infection. Owners often notice increased frequency of urination or small spots of blood in the urine and understandably assume it’s ‘just cystitis’. In practice, this is one reason urine testing and imaging are so important, especially in dogs with recurring urinary signs.

“Male dogs with bladder stones always make me slightly more cautious because of the risk of urethral obstruction. Some dogs can deteriorate surprisingly quickly if they become blocked, so changes such as repeated straining without producing urine should never be ignored.”

Emma Chandley BVetMed PGCertSAS MRCVS

When getting a quote for Petgevity Lifetime Plus dog insurance, tell us about your dog’s bladder stones, plus any other conditions they’ve had in the past two years*.

It’s important to list your dog’s conditions when taking out pet insurance, so you increase your chances of a successful claim in future.  

Find out more about our dog insurance for pre-existing medical conditions.