Bladder stones in cats are generally uncommon but can cause urinary system problems and may lead to life-threatening urinary tract obstruction. Below we will introduce to you what cat bladder stones are, the two most common types of stones and how to diagnose, treat and prevent them.

What are feline bladder stones?

Bladder stones are essentially hard, crystalline mineral rocks that form in a cat’s bladder and are usually roughly spherical or oval in shape. People, dogs, and other animals can also get bladder stones. When one or more bladder stones form, they sometimes cause irritation of the bladder wall, leading to symptoms such as frequent urination, tight urination, painful urination, and blood in the urine. However, sometimes there may be no obvious signs of bladder stones in cats at all. The symptoms that may accompany bladder stones in cats are not the only ones. Including urinary tract infections and more. Bladder stones in cats are classified as a syndrome called feline urinary tract disease.

The greatest risk for cats with one or more bladder stones is that they can cause life-threatening urinary tract obstruction.

Because symptoms of frequent urination or blood in the urine can be distressing and potentially life-threatening for cats, any kitten exhibiting these symptoms should be examined by a veterinarian as soon as possible. If a kitten is trying to urinate when there is no urine available, especially if the cat is showing other symptoms such as lethargy, vomiting, or a loss of appetite.

Causes of feline bladder stones

Although a cat can have at least four types of bladder stones, most cases are caused by two types. One is called magnesium ammonium phosphate, or struvite. The other is called calcium oxalate. They all have different reasons.

Struvite is the most common bladder stone in cats.

These stones form in alkaline urine and often affect kittens. Cats whose diets are high in magnesium and phosphorus are more likely to develop this disease. While these stones do affect all cat breeds, some breeds, including Ragdolls, may be at higher risk. Neutered male cats are also at higher risk.

The Differences of Calcium Oxalate Stones

Calcium oxalate stones usually affect older cats over 7 years of age and only form in highly acidic urine. Ragdolls are once again a high-risk breed. As with struvite stones, diet may also be involved in the formation of calcium oxalate stones, especially if excessive calcium supplementation makes the urine too acidic. About a quarter of cats with calcium oxalate stones have high levels of calcium in their blood. Unlike struvite stones in dogs, which are often associated with urinary tract infections, neither type of stone in cats is associated with urinary tract infections.

How do feline bladder stones form?

No matter what kind of stone it is, the formation process is very similar. If too many of these minerals are excreted from solution in the urine, they can collect in the bottom of the bladder and form a sandy sludge. This irritates the bladder wall, causing a mucus secretion response. Sandy/silty crystalline particles mix with mucus particles and over time, stones form. For example, take a glass of water and add some salt to it. If you only add a small amount, the salt will dissolve in the water. But if you continue to add salt, the mixture will become oversaturated and you'll see the salt start to collect at the bottom of the cup. This is similar to what initially occurs in a kitten's bladder.

Treatment of feline bladder stones

As mentioned before, any cat showing signs of abnormal urinary behavior should be taken seriously to determine which of several possible causes is the culprit. This usually begins with collecting and evaluating a urine sample. With calcium oxalate stones, the pH of the urine will be acidic. With struvite stones, the pH of a cat's urine is alkaline. Calcium oxalate stones or struvite crystals may be found when urine is examined under a microscope, although this is not always the case. Urinary crystals may appear when there are no stones, and stones may occur when there are no urinary crystals.

The results of a urinalysis may prompt your veterinarian to use x-rays or ultrasound to evaluate for bladder stones. On an X-ray, bladder stones appear as bright white objects. On ultrasound, stones block the passage of sound waves, causing a characteristic black shadow at the base of the bladder. When bladder stones are identified, there are several treatments available, each with their own pros and cons.

Bladder stones are uncomfortable for cats and present a risk of urinary tract obstruction, especially in male cats, so they should be removed as soon as possible. The fastest way is surgery, which is called a cystotomy. Many general veterinarians perform this procedure, and most kittens recover well.

The second main form of treatment is to try to dissolve the stones with diet. While this can be successful, there are some drawbacks. First, only struvite stones can be dissolved through diet. Calcium oxalate stones cannot and must be removed surgically. Since there is no 100% reliable way to know the type of stone in advance, there is about a 50/50 chance that a dissolution diet will be successful. The second disadvantage of dieting is that it takes a long time, usually taking several weeks to work, sometimes at least 2 months. During this time, the kitten may continue to show signs of inappropriate urination.

In female cats, stones can be flushed out of the bladder using a special technique called micturition. However, like bladder surgery, this method requires anesthesia and can only be used for very small stones. Because even small stones can become lodged in a male cat's urethra, this method is not common in male cats.

How to prevent bladder stones?

The most reliable method is to feed your cat as little food as possible with low magnesium and phosphorus content. The purpose is to keep the urine pH neutral. Both calcium oxalate stones and struvite stones can be prevented with a prescribed diet. For the diet to work, it must be eaten on its own. When a prescription diet may not be affordable, or the cat at home is a picky eater, try to increase the moisture content of the food and water intake to keep the urine more dilute.

This can be accomplished by increasing the proportion of wet foods in the diet, adding water to dry foods, and encouraging greater water intake through multiple water bowls and running water sources. Unfortunately, these methods alone are unsuccessful, and stones can come back. Less commonly, an underlying disease may also be present, requiring treatment to prevent stones from forming. For example, idiopathic hypercalcemia in cats leads to the formation of calcium oxalate stones.

Conclusion

Bladder stones in cats are generally less common than some other urinary tract diseases, such as urinary tract infections and idiopathic cystitis, but are still a risk factor for urinary tract disease and urinary tract obstruction. Whenever a kitten shows signs of frequent urination, inappropriate urination, or straining at home, it is important to have the problem evaluated by a veterinarian as soon as possible. Remember, if a kitten seems to be trying to urinate without producing any urine, this should be considered an emergency and requires immediate veterinary attention.