Which type of crystals is most commonly associated with urinary tract infections (UTIs)?

Struvite crystals are most commonly associated with urinary tract infections (UTIs) due to the alkaline environment created by the bacteria during infection, particularly those that produce urease. Urease is an enzyme that hydrolyzes urea, which can lead to an increase in urine pH. In this alkaline condition, magnesium, ammonium, and phosphate can combine to form struvite crystals, also known as triple phosphate crystals.

The presence of struvite crystals can indicate that a pet has a urolith (bladder stone) that may have developed as a result of chronic UTIs. These crystals can become a significant health concern as they can lead to additional complications, such as urinary blockages.

Calcium oxalate crystals, whether dihydrate or monohydrate, are typically associated with other clinical conditions rather than UTIs, and while calcium carbonate crystals can be observed in certain species of animals, they are not specifically linked to urinary tract infections. Thus, the predominant association of struvite crystals with UTIs makes them the correct answer in this context.