Bladder Stones
What Are Bladder Stones?
Bladder stones (also known as uroliths or cystic calculi) are solid formations made up of minerals that form in the urinary bladder. These stones can vary in size, ranging from tiny grains of sand to larger pieces resembling gravel. It is not uncommon to find a combination of small and large stones within the bladder.
What Clinical Signs Point to Bladder Stones?
Bladder stones in dogs can be identified through certain clinical signs. The most common signs include hematuria, which is the presence of blood in the urine, and dysuria, which is when the dog strains while urinating. Hematuria occurs because the stones rub against the bladder wall, causing irritation and damage to the tissue, resulting in bleeding. Dysuria can be caused by inflammation and swelling of the bladder wall or the urethra, muscle spasms, or physical obstruction of urine flow. It is believed to be a painful condition, as humans with bladder stones also experience pain. Many dog owners have noticed significant improvement in their pet's activity levels after surgical removal of bladder stones, indicating the discomfort caused by the condition.
Sometimes, larger stones can act like a valve, causing intermittent or partial obstruction at the neck of the bladder where it connects to the urethra. On the other hand, smaller stones can travel into the urethra and get stuck, leading to an obstruction. When an obstruction occurs, the bladder cannot be completely emptied, and in severe cases, the dog may not be able to urinate at all. If the obstruction is not relieved, it can even lead to bladder rupture.
A complete obstruction is a serious and life-threatening situation that requires emergency treatment. You can identify a urinary obstruction in a dog that is straining to urinate but unable to produce any urine or only producing small squirts of urine.
How Do Bladder Stones Form?
Bladder stones can form due to various reasons, with the Precipitation-Crystallization Theory being the most widely accepted explanation. According to this theory, certain crystalline compounds that contribute to stone formation are found in high concentrations in the urine. This can be a result of dietary choices, past bladder infections, or even metabolic issues within the body. When the levels of these compounds surpass a certain threshold, the urine becomes saturated and unable to retain any more of the compound. The saturation point is influenced by the specific minerals present in the urine and its pH levels. As a result, the excess compounds precipitate out of the solution, forming small crystals. These sharp crystals can irritate the bladder lining, leading to the production of mucus. Over time, the crystals and mucus combine to create clusters that eventually solidify into stones.
Bladder stones have the potential to form within a matter of weeks or they may require several months to develop. The rate at which they grow typically relies on the amount of crystalline material and the level of infection present. While it usually takes months for a substantial stone to form, there have been cases where sizable stones have emerged in as little as two weeks.
How Do We Diagnose Bladder Stones?
Bladder stones can often mimic the symptoms of a regular bladder infection or cystitis. However, it's important to note that not all dogs with a bladder infection will have bladder stones. So, it's crucial not to jump to the conclusion of bladder stones based solely on these common signs.
While some bladder stones can be felt through the abdominal wall, the absence of palpation doesn't necessarily mean they're not present. Some stones may be too small to be detected this way, or the bladder might be too inflamed and sensitive for palpation.
Fortunately, most bladder stones can be identified through radiographs. However, there are certain stones that may not show up on X-rays due to their mineral composition. In such cases, an ultrasound or a radiographic contrast study, which uses dye or contrast material to highlight the stones, can be used to detect them.
How Do We Treat Bladder Stones?
There are three main treatment options for bladder stones: surgical removal, urohydropropulsion, and dietary dissolution. The choice of treatment will depend on the type of stone your dog has. Let's take a closer look at each option.
1) Surgical removal: This is the quickest way to treat bladder stones. However, it may not be suitable for dogs with other health issues or those who are at risk under general anesthesia. The stones are removed through a surgical procedure called cystotomy, where the bladder is accessed and opened. Many veterinarians perform this surgery, and dogs usually recover quickly afterward. If the stones have blocked the urethra, immediate emergency surgery is necessary to save the dog's life.
2) Urohydropropulsion: If the bladder stones are small, a special catheter can be inserted into the bladder to flush them out. This non-surgical technique, known as urohydropropulsion, may be performed under heavy sedation or general anesthesia. In some cases, a cystoscope can be used to remove small stones without the need for surgery.
3) Dietary dissolution: Bladder stones can sometimes be dissolved by feeding your dog a special diet designed for that purpose. The diet will be tailored to the specific type of stone. The advantage of this option is that it avoids surgery altogether.
Your veterinarian will discuss the pros and cons of each treatment option in more detail, taking into account your dog's individual circumstances. It's important to follow their guidance to ensure the best outcome for your furry friend.
Can Bladder Stones be Prevented?
In some instances, it is possible to prevent bladder stones based on their chemical composition. Dogs commonly develop five types of bladder stones: struvite, urate, xanthine, cystine, and calcium oxalate. Analyzing the stones for their chemical makeup, whether surgically removed or passed in urine, can help your vet recommend a specialized diet to prevent future occurrences. Regular urinalyses and urine cultures are advised if stones are caused by a bacterial infection, to detect any sub-clinical recurrences. Periodic bladder X-rays or ultrasounds may also be necessary to monitor for potential reoccurrences. Early detection allows for adjustments in diet or medication before surgery becomes necessary.