What are bladder stones?
Bladder stones (also known as uroliths) are a relatively common canine urinary problem. They’re characterised as rock-like, mineral crystals that develop in your dog’s urinary tract. These may occur in the kidneys, ureter, gall bladder or urethra, but are most commonly found in the bladder.
Bladder stones in dogs are often a result of excess minerals in the urine, which eventually create sediment. Over time, this then forms into crystals, which irritate the lining of the bladder and cause a mucus to form, thus clumping the crystals together to form stones. These cause discomfort and can sometimes be very painful, even requiring surgical removal in certain cases .
Various types of bladder stone crystals develop at different internal pH levels, and hence, the acidity of the urine plays a role in the formation of stones. This can be influenced by the presence of a bacterial infection, genetics, or sometimes by an inappropriate diet.
For instance, an acidic pH level can result in the formation of cysteine stones, while alkaline levels can lead to struvite stones in some dogs. Since diet can significantly influence internal pH levels, it is crucial to consult your vet for an accurate diagnosis of the specific type of bladder stones or crystals before considering any dietary adjustments or supplements.
What causes bladder stones in dogs?
There are multiple culprits that contribute to the formation of bladder stones in dogs. Here are some of the most common causes:
- Bacteria in the urinary tract
- High mineral content in the urine
- Genetics/breed (some breeds are also more prone to certain types of stones)
- Bladder inflammation
- Living with people who smoke (due to cadmium exposure)
- Liver shunt
Bladder stones in dogs are a product of crystals (formed by mineral salts) excreted into the urine via the kidneys. There are at least 5 types of crystals in dogs which can attach to each other to form stones. These are the most common:
Struvite — Most common type and mainly found in female dogs, dogs on processed food diets, and dogs with untreated urinary tract infections (UTIs)
Urate — More common in breeds such as Dalmatians and Bulldogs or dogs with liver shunts (due to not being able to process purines)
Cysteine — More common in bull breeds due to a genetic defect that prevents reabsorption of cysteine (amino acid) from the kidneys, causing build-up in the urine
Calcium oxalate — A result of oxalates in the urine binding to calcium to form stones. More common in smaller breeds like Bichons and Yorkies
Silica — Often a result of silica in drinking water, as well as certain diets
Any dog can get bladder stones, but the below breeds are more prone to specific stones due to various genetic factors. Males generally struggle more than females, as the female urethra is wider (thus passing stones more easily):
Dalmatian — Urate
Bulldog — Urate and cysteine
German Shepherd — Silica
Newfoundland — Cysteine
Shih Tzu — Struvite
Yorkshire Terrier — Struvite
Miniature Schnauzer — Calcium oxalate
Bichon Frise — Struvite
While this information may understandably cause concern, not all dogs of the above breeds suffer with bladder stones. Don’t worry; I’ll discuss some helpful solutions and prevention tips later in the article.
Symptoms and signs to watch for
Although our canine friends can be masters when it comes to hiding discomfort, the most common signs of bladder stones in dogs are as follows:
- Difficulty urinating, frequent attempts with less production than usual, straining (Dysuria)
- Sudden or new urinary incontinence
- Blood in the urine (Haematuria)
- Cloudy urine or unusual/new urine odour
- Obsessive licking of the urinary area/genitals
- Recurring urinary tract infections (UTIs)
Canine urinary problems warrant swift veterinary attention. If your dog is displaying these symptoms, consult with your vet as soon as possible.
Important: Complete urinary obstruction is a life-threatening emergency. If your dog can’t urinate at all, take them to your vet immediately.
Diagnosing bladder stones in dogs
If your dog is showing any of the above symptoms, it is important to consult a vet immediately. If possible take a urine sample with you as this may save time. Your vet may use the following methods to diagnose crystals or stones:
- Testing urine microscopically – looking for bacteria, blood, crystal, white blood cells
- Taking a culture to confirm the type of bacteria or crystals
- Radiographs or abdominal ultrasound if stones are suspected