My cat has struvite crystals in his urine. What does this mean?

Our question this week was:

Dr. Debra – what should I do about my cat has struvite crystals in his urine. He is 3-years-old and in good health. He is a real sweetie –his name is Sammy.

Stephanie Mills – Idaho


Hi – thanks for your email Stephanie. You asked about the significance of struvite crystals in your cat’s urine.

Crystals are defined as a “solid in a liquid”. In this case it means that they crystal is in the form of a mineral or electrolyte in urine. Several things influence crystal production. These factors include the body pH (some crystals form readily in acidic urine and others in neutral or alkaline urine), temperature of the urine (crystals tend to form when the urine cools below body temperature), dietary factors (certain foods can affect pH and urine production – even the time of feeding is thought to influence pH and crystal formation, when urine is gotten relative to food intake, several drugs can cause crystal formation, as well as other factors.

Crystals by themselves are not a problem. Some normal pets have urine crystals. However, some crystals (such as struvite) can form uroliths (stones) when certain bacteria are present. This is more common in dogs than cats.

The reason struvite crystals are concerning in cats is because some cats can group debris and crystals and form a plug. This plug can get caught in the urethra (tube that takes urine out of the body) causing a life-threatening urinary obstruction. This is more common in male cats because their urethra is longer and narrower. Struvite crystals are a concern because the majority of plugs that form are made of struvite as the main component.

Many veterinarians will treat this by diluting the urine (encouraging water intake and offering canned foods) as well as feeding a diet with ingredients that are less likely to cause struvite stones (some diets also affect the pH – as struvites more commonly form in alkaline urine therefore diets that lower the pH will help to minimize struvite crystal formation).

I know that was a long answer but I hope it answers your question. If your cat is healthy and doing well – I’d probably have a repeat urine done on your cat to determine if it is persistent and work to increase his water intake. If the crystals persist or your cat has a history of urinary problems, then dietary therapy may be beneficial (such as Hills ® Prescription Diet C/D-s).

Articles that might be helpful to you are Feline Lower Urinary Tract Disease and Urolithiasis-Struvite in Cats.

Best of luck!

Dr. Debra