Accumulation of mineral salts, most commonly calcium carbonate in urine can cause the formation of urinary calculi or stones (uroliths) in the kidney, ureters, or bladder. Symptoms are frequent urination and straining. Renal colic may result from stones in the kidney travelling down a ureter. Diagnosis is confirmed by rectal examination and ultrasound. Treatment may involve manually breaking up the stone(s) or surgical removal for bladder stones. Incidence is 75% geldings and stallions due to their longer urethra, the short urethra of mares facilitating the passage of small calculi. Following removal, special diets designed to slightly acidify the urine may help reduce recurrence.