Urinary Bladder Stones in Dogs; Types and Treatment

Bladder stones can form in dogs just like they do in humans. The stones themselves (uroliths or calculi) can be described as rock-like collections of minerals that form in the urinary bladder. They may occur as a few large stones or as collections of multiple small stones. Some patients with bladder stones show no signs of any kind and the stones are discovered incidentally but there are some changes that might promote a search for stones.

Urinary Bladder Stones can be large or small and smooth or roughened depending on type. Most stones can be easily detected by a routine X-ray of the abdomen. The two most common stones, struvite and calcium oxalate are called radiodense, so they show up white on the X-ray. Two other, less common stones made of urate and cysteine are radiolucent and cannot always be seen on an X-ray without using a dye in the bladder to outline them.

Common Types of Urinary Bladder Stones in Dogs

1. Struvite

Struvite stones can often be completely dissolved in both dogs and cats using special diets. These diets encourage greater water consumption, contain controlled amounts of protein and certain minerals, and also alter the acidity of the urine. While the protocols for dissolving stones are similar between dogs and cats, prevention of future stones is quite different.

Struvite stones in dogs are usually caused by urinary tract infections and a special diet is *not* needed for dogs with struvite stones once the stones are either dissolved or surgically removed. If your dog has recurrent bladder infections that led to struvite stones, aggressive treatment is critical to resolve and prevent further infections to ensure more stones do not form.

Treatment

Your vet will likely suggest nutritional dissolution of the struvite stones — in other words, they will recommend feeding a food that is formulated to help these stones dissolve. Be sure to ask your veterinarian if a therapeutic food is a good option for your dog.

One possible theory that your vet may recommend is a procedure called lithotripsy, a procedure that uses sound waves to break up the stones.

The last possible form of treatment is through surgical removal of the stones

2. Calcium Oxalate Stones

With calcium oxalate stones, there is a strong hereditary component to formation. Certain dogs may be genetically predisposed to produce defective nephrocalcin, which is a substance in urine that naturally inhibits the formation of calcium oxalate stones. However, dogs without a genetic propensity can still develop calcium stones.

Certain breeds, such as schnauzers, are more prone to have this problem. Oxalate stones may also form if the pet has a tumor of the parathyroid gland or another type of cancer.

Treatment

The only treatment for these type of bladder stones is surgical removal. This is the easy part, its preventing their recurrence that is difficult. The protocol in how to do this was shown earlier.

3. Urate and Ammonium Urate

This is a common urolith found in Dalmatians around middle age, with males affected much more often than females. This is because they metabolize protein differently in the liver, with the end result being uric acid buildup in the urine. In addition to their high prevalence in Dalmatians, they are found in Bulldogs and Yorkshire terriers.

Treatment

If there is no PSS these uroliths can sometimes be handled medically also. A food called Hills U/D should be used. It is low in purines and has restricted protein. A medication called allopurinol is given which helps minimize the amount of uric acid produced in the urine. Potassium citrate is also used to make the urine less acidic, although this might occur with the use of U/D alone. Adding salt to the diet or mixing water with the food will also promote urination of the urate crystals. Recurrence is common, so this diet needs to be used for the life of your pet, especially in Dalmatians. We will talk more about this later in the prevention section.