Calcium Oxalate Struvite Crystals In Cats

Struvite specifically is a material that is composed of magnesium ammonium and phosphate.

Calcium oxalate struvite crystals in cats.

The cornerstone of treatment is to increase water consumption to dilute the urine and promote urine specific gravity of less than 1 020 and urine ph of 6 8 7 5. Struvite crystals develop in concentrated urine once the urine becomes supersaturated crystals aggregate to form stones. Now a cat is just about equally likely to develop struvite or calcium oxalate bladder stones. Cats who have had calcium oxalate crystals are at increased risk of a recurrence.

Cats with calcium oxalate bladder stones tend not to have crystals in their urine while those with struvite stones do tend to have struvite crystals in their urine. The very diets we use to dissolve struvite have put cats at increased risk for calcium oxalate stones. Struvite crystals are microscopic crystals that are found in the urine of some cats. Unfortunately this change isn t simply due to a decrease in the number of struvite stones.

Once the stone is formed it increases in size over weeks or months. 35 of cats with calcium oxalate bladder stones have elevated blood calcium hypercalcemia. The crystals themselves can be perfectly normal but become problematic when they combine to form grit or stones of varying shapes and sizes. A generation ago struvite crystals and stones were commonly found in cats with urinary tract disease with calcium oxalate stones and crystals relatively rare.

Protocols must be put in place to decrease the incidence after initial treatment. Although this diet did benefit many pets several cats started developing calcium oxalate stones due to the dietary change. However it is important to know which crystals a cat has so that we can tailor our treatment as the crystals form for different reasons and respond to different therapies. To reduce the incidence of struvite stone formation the cats were fed diets that had lower amounts of magnesium.

A cat affected with struvite crystals calcium oxalate crystals or any other type of crystal will suffer from the same array of symptoms and are affected in the same way. In the past most pets used to suffer from struvite stones. Less common stones include ammonium biurate cystine and uric acid. Most calcium oxalate stones develop in cats between ages 5 and 14 years.

Because struvite or magnesium ammonium phosphate crystals formed because of too much alkalinity in the feline diet commercial pet food manufacturers began acidifying their products.