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Problems associated with bladder stones (the condition is called canine urolithiasis) are not uncommon in dogs. Signs can occur suddenly, with a distressed and uncomfortable dog trying to pass urine, or can be vague and intermittent, especially in the early stages.

If you suspect your dog is unable to pass urine, seek immediate veterinary advice.

What are bladder stones and how do they form?

The X-ray below shows a dog lying on her side, facing left. Her spine runs along the top of the picture, tail heading off top right and the pelvis and the bones of the hind legs on the right (spot the knee caps) – but can you see bladder stones? Answers at the bottom…….

Bladder stones (or uroliths) form when substances dissolved in the urine take shape as tiny crystals, which come together to form visible stones. The substances which form these include minerals such as calcium, phosphorus and magnesium; others include ammonium and urate.

Uroliths vary in size from minute particles to sizeable stones measuring as much as 7 centimetres across. A stone of this size has been found (and successfully removed) from a dog the size of a toy poodle!

Why do bladder stones form in dogs?

Why and how stones form is complex and affected by many factors; for example, because:

  • Minerals are present in the urine in higher-than-normal amounts
  • The urine acidity has changed, due to a urine infection or a change in diet
  • There is bladder disease, such as inflammation or cancer
  • There are problems with the patient’s metabolism, such as high blood calcium levels
  • There is a breed-related issue, such as the Dalmation's tendency to form urate crystals

When the mineral salts form tiny crystals (known as a precipitate), these can irritate the lining of the bladder and increase the amount of mucus produced. Over time, crystals and mucus clump together and harden, forming stones that gradually enlarge. 

How would I know if my dog had bladder stones?

Sometimes you might not, for a very long time! Some stones form with very smooth surfaces so that they cause little irritation; they may gradually build up inside till they are finally discovered to be taking up most of the bladder’s capacity. Others make much more spikey shapes which are likely to irritate. Whether or not there is a urine infection present may also make a difference.

Signs of bladder stones, which may also pass into the exit tube (urethra), include:

  • Taking longer than usual to pass urine or passing a smaller stream
  • Blood in the urine, present throughout it or just at the end of urination
  • Repeated attempts to pass urine or frequently asking to go outside
  • Difficulty or discomfort passing urine
  • Dribbling urine or straining but failing to pass urine

The stones can cause irritation of the bladder lining, which can cause obvious bleeding or the signs of cystitis. Stones may get lodged in the bladder neck, causing urine leakage or straining; some dogs spurt urine or pass an intermittent, stop-start stream.

Very small stones may pass out in the urine unnoticed, but in-between sizes may get stuck in the urethra (most likely in male dogs) causing a complete blockage which can be life-threatening.

Remember, if you suspect your dog is unable to pass urine,

seek immediate veterinary advice.

How are bladder stones in dogs diagnosed?

Bladder stones are diagnosed with a combination of the signs, by seeing them on X-ray or ultrasound scan and, sometimes, in a very relaxed or sedated dog, by feeling them in the bladder. This must be done very carefully to avoid damage to the bladder lining, so don’t try this at home!

Can bladder stones in the dog be treated?

Yes, they can, though the best treatment varies with the type of stone present.

Some stones can be dissolved using special diets, if it is known what type of stone is present and if that type is suitable for dietary management. The big advantage of this is that it avoids surgery; the downside is that it takes time (several weeks or months, depending on stone size). As the stones get smaller, there is a risk that they will block the urethra, which is an emergency situation, so it is important that urination is watched and monitored. The special dissolution diets are generally more expensive than mainstream foods and they must be fed exclusively for several months to work.

Surgical removal is the other way to treat bladder stones. This is necessary if:

– the type of stone is unknown or likely to be a mix of different crystals

– the stones are very large

– the patient is in pain or discomfort

– there are signs of urethral blockage

What does surgery for bladder stones in dogs involve?

Under general anaesthetic, an incision is made, first in the abdominal wall, then in the bladder itself and the stones are carefully removed. A urinary catheter is introduced into the urethra and passed all the way into the bladder to ensure there are no small stones blocking the urethra or hiding in the bladder neck. 

Recovery from surgery is usually quick and uncomplicated, with most patients making a full recovery within 2 weeks. However, complications are possible (anaesthetic issues, infection, problems with healing, the dreaded cone of shame) and it is important that you discuss the pros and cons carefully with your vet.

What can I do to stop bladder stones coming back?

Ideally, any stones removed will be carefully analysed by the laboratory. What they are made of will affect whether specialist diets are likely to prevent – or reduce the risk of – a recurrence. Stone types include struvite, urate, cystine and calcium oxalate. There are a number of precisely formulated diets available to treat some of these, such as Hills U/D Urinary Care and Hill’s C/D Urinary Care for Dogs, or Royal Canin Urinary U/C and Royal Canin’s Urinary S/O ranges.

If a urinary infection – a bacterial cystitis – is thought to be contributing to the problem, then a course of antibiotics followed by regular urine checks and testing may be necessary to keep recurrence at bay.

Increased water intake is always helpful to reduce the chances of further bladder stone formation. Crystals form in concentrated urine, so encouraging your pet to drink more or adding wet food to the diet can reduce the chance of further stones.

Did you spot the stones?

The highlighted area shows the bladder wall outlined in red, and 4 large stones within the bladder.

We are here for you

If you think your dog may have bladder stones and would like advice on what to do, or have had problems and wish to look further at treatments and prevention, we’d be delighted to talk to you. Book a consultation with Vet on the Net to discuss your concerns from the comfort of your own home.