Bladder Stones (Urolithiasis) Part 1

This is a condition frequently seen in dogs and cats and in both males and females. Stones can develop anywhere in the urinary tract: the ureters ( 2 small tubes that carry urine from the kidneys to the bladder), the bladder which stores the urine, and the urethra which takes the urine  from the bladder to outside the body. Over 85% of the times,  stones develop in the bladder. (Very rarely do stones develop in the kidney in dogs and cats, called renal calculi.  Humans get renal calculi and not bladder stones.) In dogs and cats, certain minerals can precipitate out of the urine and become a sandy particle,  more can develop and when they cling to each other a calculus (urolith, stone) develops. They can become 3-4” in diameter and can take up to 99% of a bladder. The largest one I every removed was the size of a goose egg and it took up the majority of the bladder. It was in a female standard poodle. Most stones develop as the result of a bladder infection known as cystitis. Diet is involved as the diet influences the ph (level of acidity) and the mineral content of the urine. Water is involved because if the urine is very concentrated from lack of water consumption, more precipitates occur.  And the breed is involved because certain breeds are predisposed to calculi development. These breeds include: Schnauzers, Lhasas, Yorkies, Bichons, Shihtsus, and mini Poodles.  In male dogs and cats, the urethra is long and narrows at the penis where stones can get stuck and cause a complete obstruction. This obstruction must be relieved, urine must flow, or else it can become fatal. The stones can get stuck near the neck of the bladder, or by the prostate as it narrows going through,   midway down the urethra where it curves, or just behind the penis, (dogs have a bone in the penis known as the os penis, and the urethra is very small there). Early signs of bladder stones are the same as cystitis: frequent urination of small quantities, blood in the urine, urinary accidents, and apparent straining to urinate. The worse sign is attempting to urine but nothing comes out.  Occasionally the bladder stones can be felt with gentle palpation of the lower abdomen, and often a urinalysis shows crystals in the urine which are the precursors of calculi, but usually x-rays are taken to confirm the diagnosis.  If  crystals show up in the urinalysis, and even if very small calculi are present, surgery is sometimes avoided by just changing the diet, especially in females. Small stones in males are the most dangerous ones because of the obstruction possibility.