North American Veterinary Licensing Examination (NAVLE) Practice Test

What type of bladder stones are cats most likely to have based on their urine pH?

1. Calcium oxalate

2. Struvite

3. Cystine

4. Urate

The correct answer is: Struvite

Cats are most likely to develop struvite bladder stones, especially when their urine is alkaline (higher pH). Struvite stones are composed of magnesium ammonium phosphate and tend to form in urine with a pH above 7. They are often associated with urinary tract infections caused by urease-producing bacteria, which can further increase urine pH. In cats, struvite stones are particularly common because they can have dietary components that lead to alkaline urine, such as high protein diets. Additionally, conditions like feline idiopathic cystitis could lead to more alkaline urine and thus promote struvite stone formation. Other types of bladder stones do exist in cats, but they are less frequently diagnosed. Calcium oxalate stones are formed in more acidic urine and are becoming more prevalent, particularly in some subsets of the cat population. Cystine and urate stones are rarer in cats, with cystine stones associated with a genetic defect leading to an inability to properly reabsorb cystine, usually resulting in more acidic urine. Urate stones are typically associated with conditions that cause liver dysfunction or are congenital in certain breeds. Thus, struvite stones stand out as the most common bladder stone found in cats due to the normal p