Urolithiasis refers to the formation of stones (calculi or uroliths) in the urinary tract. Calculi can be found anywhere in the urinary tract, in the kidneys, the ureter or the bladder, but are most common in the bladder. They are most commonly found in rabbits and ferrets but can also affect smaller animals.
Calculi form due to oversaturation of the urine with certain minerals. Several factors may contribute to this oversaturation including increased concentrations of specific minerals in the urine, alterations in the pH (acidity or alkalinity), highly concentrated urine, presence or absence of stimulators, and inhibitors of crystal formation.
Several factors can contribute to development of urolithiasis. These include:
The cause for stone formation is unknown in many cases.
The various types of calculi are named according their predominant mineral composition. The different types of calculi must be treated differently. Consequently, it is important for your veterinarian to be able to obtain calculi for chemical analysis.
The risk of recurrence for urolithiasis is high and ranges from 20 to 50 percent. The pet's symptoms depend upon the number of stones, their location in the urinary tract, the physical characteristics of the stones (smooth or jagged), and the presence of bacterial urinary tract infection.
What to Watch For
Diagnostic tests are needed to identify urolithiasis as the cause of your pet's symptoms and to exclude other disease processes.
A complete medical history and physical examination, including palpation of the abdomen, is essential in all sick animals. For many small mammals, a physical exam may be all that is necessary to suspect bladder stones. If possible, additional tests will help confirm the diagnosis, such as:
In a few cases, additional tests may be recommended for ferrets and rabbits. These are rarely, if ever, performed on most small mammals:
Treatments for urolithiasis may include one or more of the following. For rabbits and ferrets, more aggressive treatment is possible. Due to size and cost concerns, surgery is often not performed in rodents:
Some stones can be dissolved by dietary means and others cannot. Whether or not to attempt dietary dissolution will depend on your pet's general health, the type of stone suspected, the location and number of stones and other factors that your veterinarian will discuss with you.
In many instances, surgery is the most direct way to remove stones and submit them for analysis.
Home Care and Prevention
At home, be sure to administer any medications prescribed by your veterinarian. Give antibiotics according to the schedule prescribed. It's important to allow your pet free access to fresh clean water.
Most stones are difficult to prevent. Providing your pet with frequent opportunities to urinate and an ample supply of fresh clean water may help.
Prompt treatment of urinary tract infections can help reduce the potential for certain stone formation.