Feline Urolithiasis (Stones in the Urinary Tract)
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.
Below is an overview of Urolithiasis in cats followed by in-depth detailed information on the diagnosis and treatment of this condition.
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 various types of calculi are named according their predominant mineral composition. In cats, calculi composed of the minerals magnesium ammonium phosphate (commonly called struvite) and calcium oxalate are most common. Urate calculi occur less commonly. Cystine and silica calculi are relatively rare. 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
Symptoms caused by kidney stones include back or abdominal pain or occasionally abnormal odor to the urine if bacterial infection is present. Surprisingly, however, many pets with kidney stones have few or no symptoms.
Diagnosis of Urinary Tract Stones in Cats
Diagnostic tests are needed to identify urolithiasis as the cause of your pet’s symptoms and to exclude other disease processes. Your veterinarian may recommend:
Other diagnostic tests that may be completed include:
Treatment of Urinary Tract Stones in Cats
Treatments for urolithiasis may include one or more of the following:
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.
Follow-up with your veterinarian for physical examinations and urinalysis as directed. Urine culture should be repeated 5 to 7 days after completion of antibiotic treatment to ensure eradication of infection. If your pet has a poor response to treatment, further workup may be required to search for underlying disease processes.
Stone analysis will guide your veterinarian’s treatment plan: