What is a Bladder Stone?
Bladder stones (uroliths or cystic calculi) are rock-like formations of minerals that develop in the bladder. There may be a large, single stone or several stones that range in size from sand-like to gravel. It is common for a mixture of both small and large stones to be present. They can happen in cats and dogs, males and females although females are over-represented!
What other kinds of stones are there?
Gall stones form in the gall bladder and contain bile salts. Kidney stones (nephrolith) are mineralized formations that develop in the kidney.
What are the clinical signs of bladder stones?
The most common signs that a dog has bladder stones are hematuria (blood in the urine) and dysuria (straining to urinate). Hematuria occurs because the stones rub against the bladder wall, irritating and damaging the tissue and causing bleeding. Dysuria may result from inflammation and swelling of the bladder walls or the urethra, from muscle spasms, or due to a physical obstruction to urine flow caused by the presence of the stones. This condition can be very uncomfortable and even painful.
Large stones may cause an intermittent or partial obstruction of the bladder. Small stones may flow with the urine into the urethra (Urethrolith) where they can become lodged and cause an obstruction. If an obstruction occurs, the bladder cannot be emptied fully; if the obstruction is complete, the dog will not be able to urinate at all. If the obstruction is not relieved, the bladder may rupture. A complete obstruction is potentially life threatening and requires immediate emergency treatment. A urinary obstruction will usually be recognized in a dog that is straining to urinate without producing any urine, or is only producing small squirts of urine.
How did my dog get bladder stones?
There are several theories of how bladder stones form. The most commonly accepted theory is called the Precipitation-Crystallization Theory. This theory states that one or more stone-forming crystalline compounds is present in elevated levels in the urine. This may be due to dietary factors, previous disease like a bacterial infection, problem with the body’s metabolism, or other diseases such as liver disease. When the amount of this compound exceeds a threshold level, the urine becomes saturated and the excess precipitates out of solution and forms tiny crystals. The sharp crystals irritate the bladder lining, causing a production of mucus. The crystals and mucus stick together, forming clusters that gradually enlarge and harden into stones. This is similar to the way “rock candy” is formed.
How quickly can bladder stones form?
Bladder stones can develop within a few weeks or they may take months to form.
How are bladder stones diagnosed?
Some bladder stones can be palpated (felt with the fingers) through the abdominal wall. Most bladder stones are visible on radiographs or an ultrasonic bladder examination. Rarely bladder stones are not visible on radiographs because their mineral composition does not reflect x-ray beams.
How are bladder stones treated?
In general, there are three main treatment options for bladder stones: surgical removal or dietary dissolution.
Option 1: Surgical removal of bladder stones. This is often the quickest way of treating bladder stones; however, it may not be the best option for patients that have other health concerns, or in whom general anesthesia could be risky. With this option, the stones are removed via a cystotomy, which means that the bladder is surgically exposed and opened so that the stones can be removed. Dogs usually make a rapid post-operative recovery.
Option 2: Dietary dissolution. In some cases, bladder stones can be dissolved by feeding the dog a special diet that is formulated to dissolve bladder stone(s). This diet will be tailored to the specific type of stone that is present. The advantage of this option is that it avoids surgery. It can be a very good choice for some dogs. However, it has three disadvantages:
- It is not successful for all types of stones.
- It is slow. It may take several weeks or a few months to dissolve a large stone so the dog may continue to have hematuria, dysuria, and recurrent infections during that time. The risk of urethral obstruction remains high during this period
- Not all dogs will eat the special diet. These diets will not work unless they are fed exclusively. This means that NO TREATS or supplements can be given to your dog while it is on the special diet.
Can bladder stones be prevented?
Periodic bladder x-rays, urinalysis, or ultrasounds may be helpful in some cases to determine if bladder stones are recurring.
Early recognition may allow your veterinarian to adjust your dog’s diet or medications before your pet requires surgery. If your pet has been having unusual urination or has had previous issues with blood in their urine please call Meadowlands Veterinary Hospital at 201-646-2008 to make an appointment to have your pet checked by the doctor.
This client information sheet is based on material written by: Ernest Ward, DVM