urolith

See urinary calculus.

A calculus in the urine or the urinary tract. See also urolithiasis.

• apatite u's — consist of calcium phosphate in several forms, the most common being hydroxyapatite and carbonate-apatite. They may be only a component of uroliths of other mineral composition or occur in association with primary hyperparathyroidism, excessive intake of calcium and phosphorus or renal tubular acidosis. They are smooth and radiopaque.
• ammonium acid urate u's — the common form of urate uroliths in dogs. Occur particularly in Dalmation dogs because of their unique urate metabolism which results in high urinary levels of uric acid.
• barium u's — rare, iatrogenic curiosities.
• brushite u. — calcium hydrogen phosphate dihydrate.
• calcium phosphate u's — apatite uroliths.
• carbonate u's — found in ruminants with alkaline urine that ingest high-oxalate plants or pasture that is dominated by clover.
• clover u's — occurs in wethers grazing estrogen-rich clover pasture. May be a soft yellow body composed of benzocoumarin, a metabolite of estrogens in the subterranean clover, and desquamated epithelial cells or a pasty white material consisting largely of calcium carbonate and organic matter derived from isoflavones. Called also clover stone.
• cystine u's — occur in dogs excreting high levels of cystine in their urine due to an inherited transport defect in the proximal renal tubules.
• u. dissolution — may be part of the management of struvite and cystine uroliths in dogs. It involves increasing the solubility and reducing the quantity of crystalloids in the urine and increasing the volume of urine by the use of urinary acidifiers, dietary changes and promoting diuresis. See also calculolytic diet, acetohydroxamic acid.
• jackstone u's — see silica uroliths (below).
• magnesium ammonium phosphate u's — see struvite uroliths (below).
• oxalate u. — hard, dense, white or yellow calculi with rough surfaces which may originate from ingested oxalate but in many cases is the endogenous product of liver metabolism.
• preputial u. — top-shaped calculi found rarely in the prepuce of steers. They have a valve-like effect and cause obstruction of the orifice, distention and sometimes local infiltration of subcutaneous tissues with urine.
• purine u's — includes ammonium acid urate, sodium acid urate and xanthine uroliths.
• renal u. — one formed in the renal pelvis and often of corresponding shape.
• silica u's — consist largely of silica. Are white to brown in color, may be laminated and measure up to 0.5 inch in diameter. They may reach a high level of prevalence in groups of wethers from particular areas and from particular farms where the silicon level in the pasture is high. In dogs, they occur with low frequency except in certain areas, particularly Kenya. They often have a characteristic appearance with numerous spiked projections from the surface. Called also ‘jackstones’.
• struvite u's — white, crumbly, smooth bodies composed of magnesium ammonium phosphate hexahydrate (triple phosphate). The most common type of urolith in dogs and cats; they are commonly associated with infection of the urinary tract. Obstruction of the urethra by crystals of struvite is common in cats. Called also triple phosphate uroliths. See also feline urological syndrome.
• urate u's — small (less than 2 inches diameter) yellow or brown calculi seen in dogs, especially Dalmatians, Bulldogs and pigs.
• urease u's — see struvite uroliths (above).
• whitlockite u. — tricalcium phosphate.
• xanthine u's — yellow to red, friable, irregularly shaped calculi in sheep and young cattle.

The noun has one meaning:

Meaning #1: a urinary stone