Diagnosis: Bladder Stones

This common condition requires prompt treatment.

Your cat normally uses the litter box a few times a day to relieve herself, but today is different. Shes going to the box every few minutes and vocalizing as she strains to urinate. The small amount of urine that finally dribbles out is filled with blood. Your cat may be suffering from bladder stones, a painful condition that, left untreated, can lead to serious illness and in rare cases, death.

Causes of Bladder Stones. Bladder stones, or uroliths, are caused by an extensive concentration of salts and minerals in the urine such as magnesium, phosphorous, calcium, and ammonia.

“There should always be a certain amount of salts and minerals in the urine,” says Richard Goldstein, DVM, an associate professor of small animal medicine at Cornell Universitys College of Veterinary Medicine. “But when the urine becomes super saturated – meaning theres an overabundance of salts and minerals – crystals begin to form.”

Once crystals have formed in a cats bladder – a relatively slow process that may transpire over several months or years – the speed at which bladder stones develop can occur at a much faster pace, given the right conditions. “This can include increased calcium concentrations in the blood and urine or increased urine concentration in general because cats often do not drink enough water or get enough moisture in their food,” Dr. Goldstein says.

Types of Bladder Stones. There are different types of bladder stones, which vary depending on their chemical makeup. The two most common stones seen in cats are: struvite and calcium oxalate.

Struvite stones occur frequently and consist of approximately 50 percent of all bladder stones. Unlike struvites in dogs – which form in response to a urinary tract infection – struvites in cats develop because of a high concentration of minerals in the urine. This usually occurs because cats are not drinking enough water or are not urinating on a regular basis. The stones that form are often large and round and are most commonly seen in younger female cats.

Calcium oxalate stones are typically smaller in size than struvite stones and have jagged edges. These stones often form in the bladder, the kidneys, or ureters (the tubes that connect each kidney to the bladder). If one or more stones become lodged in the ureter, the flow of urine from the kidneys is obstructed, resulting in acute illness. In these cases, immediate medical attention is necessary.

Diagnosis and Treatment. Luckily, veterinarians have many tools to determine the presence of bladder stones. First, a cat will need to undergo a thorough examination at a veterinary clinic, during which time a veterinarian will ask the owner for a description of the cats symptoms. He or she will then palpate the abdomen (they can sometimes feel the stones) and order one or more of the following: blood tests, X-rays, ultrasound, urinalysis, bacterial culture and, eventually, stone analysis. Once a diagnosis is made, treatment options can be discussed.

Treatment for bladder stones varies depending upon the type of stone. In some cases, struvite stones can be dissolved over time with a special diet and medication, without the need for surgery to remove the stones. A cat will often remain on the special diet for several weeks or months or, in some cases, for the remainder of her life. In other instances – especially when calcium oxalate stones are suspected or a stone becomes lodged in a male cats urethra (a long, narrow tube that connects the urinary bladder to the outside of the body) – surgery is necessary to remove them.

Calcium oxalate stones cannot be managed with diet and medication, therefore, surgery to remove the stones is the prescribed course of treatment. With that said, there is a relatively new technique called lithotripsy that works well for calcium oxalate bladder stones without the need for invasive surgery in female cats. During the procedure, high energy lasers are passed through as a narrow fiber, into the bladder, and placed right up against the stone. The laser is then used to break the stones into tiny pieces. Once the stones are shattered, they can pass through the urethra along with the urine or can be manually removed with specialized baskets.

Emergency Cases. As previously noted, the most common signs of bladder stones in cats are vocalization, difficulty urinating and blood in the urine, which is caused when the stones irritate the bladders sensitive lining. Unfortunately, many owners will misinterpret these signs and assume their cat is constipated. What is actually happening is that one or more of the stones have created a blockage in the urethra and urine is backing up in the body. At this point bladder stones can become deadly, warns Dr. Goldstein.

“If a cat – especially a male – is straining to urinate and nothing is coming out, that can be a real “get up in the middle of the night” emergency, he says. “If a cat is obstructed for even one day, he becomes very sick and there may start to be significant kidney damage.”

Preventing Problems. Because the rate of recurrence of bladder stones is relatively high even after a successful treatment, preventive measures need to be taken. This can include a special diet that alters the acidity and mineral concentrations of the urine and administering medication to mitigate new stone formation. Its also important that a cat maintains a healthy weight, has constant access to a clean litter box and drinks plenty of water.

“Encourage your cat to drink water by offering multiple water sources,” suggests Dr. Goldstein. “Electric water fountains are nice because water is constantly being circulated in the bowl and some cats are fascinated by running water.” Additionally, Dr. Goldstein suggests feeding your cat a primarily wet (canned) food diet because wet food has a high moisture (water) content, which helps keep the urine from becoming too concentrated. If your cat prefers dry kibble, try mixing dry and wet food together. “Anything owners can do to increase their cats water intake is good,” says Dr. Goldstein. “If the diet induces urine that it too acidic or too alkaline, an imbalance is created and theres a higher likelihood of crystal formation.”

While you cant always prevent bladder stones from developing, you can be diligent in observing your cats urinary habits and seeking veterinary help if you notice any changes. Dr. Goldstein points out that with early detection and proper medical management, bladder stones can be treated successfully and cats can go on to live normal, healthy lives.

“This is a condition thats very treatable and theres a lot that veterinarians can do – once the stones have been removed – to prevent a reoccurrence,” he says. “Were much better off than we were even a few years ago, but it does require persistence and the desire of the veterinarian and owner to make an effort to prevent bladder stones from reoccurring.”