For example, one of the most common kinds of stone is made up of magnesium, phosphate and ammonium. Another common type of stone is a calcium oxalate urolith. Other less common types of uroliths include urate stones, silicate stones and cystine stones. Some waste products, however, are sparingly soluble in urine. If urine becomes over-concentrated with waste products that are not very soluble in urine, minerals may precipitate to form crystals.
Crystals then build upon each other to form a base, or nidus, on which more cyrstals are deposited.
Eventually, a stone is formed. Certain dog breeds are more prone than others to develop uroliths. This suggests there may also be inherited factors involved. High risk breeds include miniature Schnauzers, Poodles, Dalmatians, Dachshunds, Yorkshire Terriers and others. Many dogs have blood in their urine or experience painful urination.