Which stone types are commonly found in feline urolithiasis?

• A. Struvite and Calcium oxalate
• B. Uric acid and cystine
• C. Silicate and xanthine
• D. Magnesium ammonium phosphate only

Answer: (A)

In feline urolithiasis, the two most common stone types are struvite and calcium oxalate. Struvite stones form in urine that is more alkaline and rich in magnesium ammonium phosphate; they used to be especially common in younger cats and are often amenable to medical dissolution with a urinary-tract–friendly diet that acidifies the urine. Calcium oxalate stones form in urine that is neutral to slightly acidic and result from precipitation of calcium oxalate; these cannot be dissolved by diet and typically require removal of the stone or other procedures, with prevention focusing on managing urinary composition and hydration. Other stone types like uric acid, cystine, silicate, or xanthine are much less common in cats, so the combination of struvite and calcium oxalate best describes what’s typically seen.