CASTLE: Bladder stones common in dogs

Published 11:47 am Wednesday, October 16, 2019

Most everyone has heard of kidney stones in people and probably knows someone who has experienced the pain of passing one of these stones.

Although dogs are similar to people when it comes to many medical conditions, kidney stones are rare in dogs.

However, bladder stones are quite common in dogs.

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The biggest difference is the location where the stones develop. Bladder stones, also known as uroliths or cystic calculi, are a collection of minerals making a rock-hard stone which develops in the urinary bladder instead of the kidneys.

Fortunately for cats, they rarely develop bladder stones. It is still possible for cats to develop bladder stones, though. Cats have plenty of their own unique urinary tract problems.

There are numerous shapes and sizes of bladder stones depending on the actual mineral composition of the stones.

The two most common types of bladder stones are called struvite and calcium oxalate stones.

The mineral composition of each type is totally different. The type of minerals present determines the treatment necessary to prevent reoccurrence of bladder stones.

It is important to have the stones analyzed by a veterinary laboratory to determine the exact mineral composition for proper diagnosis and treatment.

The most common symptoms of bladder stones are blood in the urine and straining to urinate. The stones in the urinary bladder irritate the lining of the bladder wall causing inflammation, swelling and pain.

Sometimes, the stones may cause partial obstruction of urine flow which is apparent by your dog straining to urinate.

Complete obstruction of urine flow occurs when one or more stones become stuck in the urethra. Male dogs are more prone to urinary obstruction than female dogs. On occasion, a female dog has a large urinary stone that obstructs the opening of the bladder into the urethra.

When complete obstruction occurs, not only does it cause extreme pain, it also causes toxins, normally excreted in the urine, to back up into the blood stream. This results in a sick patient and an emergency situation.

Some dogs are more prone to developing bladder stones beacuse of their genetics. Other factors may also be involved.

Untreated urinary tract infections or chronic infections could lead to stone development. Because of their genetics, some dogs will develop stones depending on what type of food they eat.

Uncomplicated urinary tract infections may present with the same symptoms. Most dogs with bladder infections do not have bladder stones.

Diagnosis of bladder stones may be evident whenever your veterinarian can actually feel the stones by feeling the abdomen.

X-rays are one of the best ways to diagnose bladder stones. However, some stones called radiolucent do not show up on an X-ray. If your veterinarian suspects bladder stones but they are not present on an X-ray, an ultrasound of the bladder may be necessary.

A urinalysis is a test performed using your dog’s urine to detect a bladder infection, but may also show microscopic crystals which could be precursors to bladder stone formation. If your dog has a urinalysis performed and microscopic crystals are found, they may be more predisposed for bladder stones.

Microscopic urinary crystals form under the same conditions as bladder stones and can bind together to form the stones. Under a microscope, these crystals look like tiny, microscopic shards of glass.

The best treatment for bladder stones is surgical removal of the stones. The actual mineral composition of the stones, as confirmed via lab tests, will determine the best preventative measures so your dog won’t develop bladder stones in the future.

Most dogs that develop bladder stones are at least a few years old. However, once I treated the most unusual case of bladder stones I’ve ever seen.

Sadie Mae is a female mixed breed (part Great Pyrenees and part Golden doodle) dog that was only eight weeks old when she presented with signs of a urinary tract infection. Unfortunately, she had a complete urinary obstruction and was becoming very sick.

We successfully performed emergency bladder stone surgery on the youngest dog I’ve ever seen with bladder stones. Sadie Mae made a complete recovery and hasn’t even had a urinary tract infection since then.

Some dogs with bladder stones may need to take medication for the rest of their life to help prevent the stones from reoccurring.

Primarily, prescription food is responsible for preventing dogs from developing bladder stones once they have been diagnosed, removed and analyzed. Those dogs that have been successfully treated must eat the prescription food for the rest of their life.

Each type of bladder stone requires feeding a special food specific for the mineral content.

Dr. Jeff Castle is a veterinarian at Clark County Veterinary Clinic.