Struvite Bladder Stones in Dogs

Struvite stones can affect not only dogs, but humans and other animals as well. As many as 85 percent of all dogs that have struvite stones are female. Some breeds are more susceptible to this condition than other breeds. Dogs with struvite stones in the bladder may not exhibit symptoms. Some dogs pass struvite stones simply, while others require veterinary treatment.

  1. Diagnosis

    • Common symptoms for struvite bladder stones include bloody urine, recurring infection in the bladder and problems urinating. A stone that passes indicates the presence of more stones. The passed stone can be analyzed so that the right treatment can be determined for other stones present in the bladder. Struvite stones show up on radiographs, so this is the most popular method of diagnosing struvite stones if the dog has not already passed a stone.

    Types

    • Types of struvite crystals differ based on mineral composition. The most common types of struvite bladder stones are struvite and oxalate, but the approach to treatment for each type is different. Struvite stones come from struvite crystals and form as a result of urinary changes that occur with bladder infections, including staph infections and proteus infections. Struvite crystals require alkaline pH to form, while oxalate crystals form with acidic pH. Oxalate crystals form when too much oxalate is absorbed into the bloodstream, allowing it to pass into the kidneys through the urine.

    Mineral Composition

    • Struvite crystals are composed of phosphate, magnesium and ammonium. Struvite crystals are also known as triple phosphate crystals. Struvite crystals are common in normal, healthy urine, and in dogs they do not typically have any consequence unless the struvite crystals and stones are accompanied by infection. Struvite crystals accompanied by infection produces urease, which makes the struvite crystals and stones more harmful.

    Formation

    • Urea is a biochemical that is excreted naturally in urine. However, when bacteria infect urine, the urea breaks down into ammonia. The ammonia ionizes into ammonium in water and is toxic to the bladder wall's cells, creating inflammation. Proteins are released through this inflammatory reaction, and the struvite crystals use the resulting matrix to form into a stone. This reaction can only take place when there is an alkaline pH in the urine.

    Treatment

    • Struvite bladder stones in dogs are removed surgically or through the use of a technique called voiding urohydropropulsion. Surgical removal is the most direct form of struvite bladder stone removal. Voiding urohydropropulsion involves filling the bladder with fluid to expel the stone. Small bladder stones may also be removed with a cystoscope or dissolved through changes in diet. Cystoscopy is more expensive. Some special veterinary diets help dissolve struvite stones and crystals through natural methods, which also dilute urine and promote good urinary tract health.