Is your dog struggling to urinate? Then you should contact your vet as soon as possible! We will clarify how bladder stones in dogs can be dangerous and how to protect your dog from them.
Bladder Stones in Dogs (Urolithiasis)
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Vets use ultrasound to make certain bladder stones visible in dogs.
Cause: What are the triggers of bladder stones in dogs?
Bladder stones are urinary stones (uroliths) found in the bladder. With male dogs, urinary stones are more likely to accumulate in the urethra and can obstruct it.
Urinary stones emerge if there is too much dissolved salt in your dog's urine. This gradually accumulates so that it initially forms sand-like grains, then crystals and finally centimetre-long stones (also called concrements).
The following factors increase the risk of bladder stones in dogs:
- Bacterial infection of the urinary tract
- Serving food that promotes urinary stones
- Genetic factors (inheritance)
- Other underlying diseases that constrict the urinary tract
- Too little water consumption
The five types of bladder stones in dogs
Vets split bladder stones into five different types:
Struvites (also magnesium ammonium phosphate hexahydrate) are the most common uroliths found in dogs. Urinary tract infections in particular are known for promoting the formation of struvite stones in dogs.
The reason is that bacteria form what are known as ureases. These are enzymes that alkalise the pH value (measure of an acidic or alkaline environment) and lead to an increased concentration of ammonia and carbon dioxide in the urine. Together with magnesium and phosphate, this forms struvite crystals in the urine.
Calcium oxalate stones (Ca oxalate stones)
Calcium oxalate stones are the second most common type of urinary stone in dogs. If your dog consumes too much calcium in its food, the kidneys will excrete it in the urine.
However, the calcium concentration in the blood can also increase if your dog has parathyroid hyperfunction (primary hyperparathyroidism) or has consumed too much vitamin D. Cancer diseases such as lymphomas can also be a cause of calcium oxalate stones.
Uric acid stones
This type is very common in Dalmatians. The breed excretes a lot of uric acid compared to others, which is why it accumulates into concrements.
Nevertheless, dogs of other breeds can also form this bladder stone, for instance, if they have a liver shunt (portosystemic shunt). This is an blood vessel abnormality that lead to an accumulation of toxic substances in the body.
If there is too much of the poorly water-soluble amino acid cystine in your dog's urine, it accumulates as cystine crystals. The risk increases if you feed your dog too many proteins, which strongly acidify the urine.
Silica bladder stones are only very rare in dogs. They develop in the urinary tract once your dog has consumed a lot of food rich in silica.
In general, mixed forms can also occur. In this case, it is advisable to have the stones examined by a special laboratory.
Symptoms: What are the signs of bladder stones in dogs?
The clinical picture depends on which urinary stone it is, how big it is and where it is located in the urinary tract. Nevertheless, the most common symptoms include:
- Urination of many small amounts (pollakisuria)
- Blood in the urine (haematuria)
- Pain when urinating (stranguria)
- If your dog doesn't excrete enough urine – including urinary toxic substances – it may show signs of intoxication (e.g. vomiting, diarrhoea, loss of appetite)
When do I have to see a vet?
Your dog no longer being able to urinate is a health emergency! Get your dog examined by a vet as quickly as possible so that they can recognise and treat a dangerous blocking of the urethra as early as possible.
To do this, the vet first positions a urinary catheter so that urine can flow out again. In addition, they will give your dog fluids and electrolytes by infusion if your dog's circulation is out of balance.
Diagnosis: How are bladder stones detected in dogs?
The vet will gently touch your dog's bladder in order to rule out perceptible changes. This allows them to assess whether your dog feels pain when it is touched.
Using imaging procedures (e.g. ultrasound or X-ray), it is possible for the vet to make bladder stones visible. Whilst calcium oxalate and struvite stones are visible on X-rays, cystine and uric acid stones are only shown during ultrasound scans. With the help of these procedures, specialists can rule out other changes like a bladder bursting with urine or congested renal pelvis.
The vet also takes a urine sample in order to be able to reliably detect the crystals. The vet examines the sample under a microscope. They can reliably identify the crystals in the urine based on typical features.
Treatment: How bladder stones in dogs are treated
There are different treatment options depending on the type of bladder stone. If bladder stones can be removed surgically due to their size and location, the vet will recommend an operation (cystotomy) in the first instance.
If a surgical procedure is not possible or the vet recommends an additional medical treatment, certain medication can dissolve bladder stones.
Urine acidifying medication helps to remove struvites from the urinary tract. Other substances are able to dissolve uric acid stones. A long-term change of diet with special dietary foods to combat bladder stones is also important to prevent a relapse.
If the vet has diagnosed a urinary tract infection, they will also fight the germs with the help of antibiotics. In order to treat the infection in a targeted manner and avoid resistance, the vet will have the germ tested in a lab for certain antimicrobial agents.
Prognosis for uroliths in dogs
Around a quarter of all operated patients develop bladder stones (recurrences) again in the near future. Hence, it's important to follow all measures to prevent recurrences in discussion with your vet.
Prevention: How to protect your dog from bladder stones
The first point is the right diet. Make sure to always feed your dog in a balanced manner. If your dog has already suffered from struvite or calcium oxalate stones, the dog food should have the following dietary properties:
- Low quantities of magnesium, phosphorous, calcium and oxalates
- Less but higher-quality proteins
Furthermore, it's important that your dog has access to fresh drinking water at all times. If urine remains in the bladder for too long, it encourages the formation of bladder stones. Hence, you should take your dog for a walk several times a day.