4 types of bladder stones that affect dogs

Is your pup straining to pee or going often in small amounts? Or perhaps you’ve spotted blood in your dog’s urine. These are all signs that they need a trip to the vet as soon as possible — and the diagnosis could be bladder stones. 

Clumps of minerals stuck together to form solid stones in your pup’s bladder (aka bladder stones) can lead to serious health issues. If not dissolved or removed, they can cause life-threatening obstructions, which is why it’s important to take your dog to a vet immediately if you notice changes in their bathroom habits.

But there are different types of bladder stones, and each affect certain dog breeds or ages more than others. Here’s why.

‍‍What causes bladder stones in dogs?

Bladder stones form for different reasons based on their type. For example, some form because of higher pH levels or bacterial infections. 

Food can play a role in developing bladder stones, too, particularly if a dog is fed a low-quality diet. “Other causes are the result of underlying abnormalities in the way the body processes certain minerals, other underlying diseases and/or excessive quantities of certain minerals in the diet,” Dr. Emily Singler, VMD, Fetch’s on-staff veterinarian, says. 

‍‍Types of bladder stones in dogs

There are four different types of bladder stones, including struvite, calcium oxalate, urate and cystine — and some affect certain dog breeds, genders and ages more than others. However, Dr. Singler says that even if a pup isn’t in a higher-risk category, they’re still able to develop them (it’s just less common). 

Calcium oxalate and struvite bladder stones, typically caused by abnormalities in the urines’ pH, are the most common bladder stone types. “Struvite stones tend to form when the urine is at a higher pH, and calcium oxalate stones tend to form at a lower pH,” Dr. Singler says.

Here's what you should know about each bladder-stone type:

‍‍Struvite

Because female dogs are particularly prone to developing urinary tract infections (UTIs), it also predisposes them to develop struvite bladder stones. “Certain bacteria can raise the urine’s pH by using an enzyme to break down urea, making struvite crystals and stone formation more likely,” Dr. Singler says. 

‍‍Calcium oxalate

Pups that have issues processing certain minerals from their diet or underlying issues that cause their calcium levels to be high commonly have calcium oxalate stones, Dr. Singler says. However, researchers are still trying to determine why these stones form in some dogs.

These bladder stones are most common in middle-aged or older, neutered male dogs — except for the Bichon Frise breed, who are prone to developing calcium oxalate stones at a younger age. 

According to Dr. Singler, Miniature Schnauzers, Lhasa Apsos, Yorkshire Terriers, Bichon Frises, Pomeranians, Shih Tzus and Miniature Poodles are at higher risk of developing calcium oxalate stones than other breeds.

‍‍Urate

Young to middle-aged dogs, particularly those who suffer from a portosystemic shunt (abnormalities in the blood vessels bypassing the liver), are most at risk for developing urate crystals. 

“When the liver isn’t allowed to function normally due to a portosystemic shunt, it can’t adequately filter toxins from the bloodstream,” Dr. Singler adds. “These substances can combine in the urine to form urate crystals, and sometimes, stones.”

But genetics can play a role in urate stones forming, particularly in Dalmatians, English Bulldogs and Russian Terriers. But, these dogs often have an enzyme mutation that takes urate stones and empties them from their body, Dr. Singler explains. 

‍‍Cystine

Both male and female dogs are at risk of forming this crystal type when their kidneys don’t absorb the amino acid, cystine. These stones can also be hormone-induced in intact male dogs (it’s still being studied by researchers as to why this happens). 

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