Which food is best for cats with urinary crystals?

Written by Sjoerd | May 12, 2025

Your vet has informed you that your cat has urinary crystals and requires a special diet to dissolve or prevent them. But with so many different urinary diets available, how do you know which one is right for your cat? We’ll explain it here.

What are urinary crystals in cats?

When a cat has urinary crystals, it means that crystals have formed in the urine. These crystals irritate the bladder wall and can lead to a bladder infection. They may also clump together into stones, which can further irritate the bladder or even cause a blockage. A vet can detect crystals through microscopic urine analysis. Stones are typically visible via X-ray or ultrasound of the bladder.

Cats can develop different types of urinary crystals. The most common are:

Struvite
Calcium oxalate

Struvite crystals

Struvite crystals are the most common type found in cats. They form when magnesium and phosphate combine in the urine, creating magnesium ammonium phosphate crystals. These develop in concentrated urine with a high pH (low acidity). Struvite is the only type of crystal or stone that can be dissolved with a specialised diet.

Calcium oxalate crystals

In contrast to struvite, calcium oxalate crystals form in acidic urine (low pH). They result from the combination of calcium and oxalate. If stones form, they cannot be dissolved and must be surgically removed. However, their formation can be prevented with appropriate nutrition.

Which diet should I feed my cat with urinary crystals?

As you’ve read, different types of urinary crystals form under different conditions. The right food for your cat depends on the type of crystal your vet has identified. A urine test is essential before choosing a suitable diet.

Food for struvite crystals

Food for cats with struvite crystals typically has the following features:

Lowers urinary pH (makes it more acidic)
Dilutes the urine
Contains fewer minerals that promote crystal formation

Examples include:

Food for calcium oxalate crystals

If your cat has calcium oxalate crystals, it needs a different diet from one used for struvite. These are usually renal diets that are low in calcium and phosphorus.

Combination diets for struvite and calcium oxalate

Urinary issues and bladder stones in cats are often complex, with multiple contributing factors such as stress or obesity. Some cats may even suffer from both types of crystals. That’s why there are combination diets available that support both types.

Stress plays a significant role in crystal formation. Hill’s has developed Hill’s c/d Urinary Stress to support both urinary health and stress management.

Additional ways to support your cat

Obesity
Lack of physical activity
Genetic predisposition
Insufficient water intake
High-sodium diet

For cats that are overweight, consider:

Cats naturally drink very little, which leads to highly concentrated urine that promotes crystal formation. Wet food can help increase fluid intake. Most urinary diets are also available in wet form, such as:

You can also try our urinary diet trial pack if your cat is picky.

To increase fluid intake, dilute wet food 1:1 with water — not all cats will accept this, but even a small improvement can help.

My cat can’t switch to a urinary diet — what now?

If your cat is already on a therapeutic diet for another condition, switching may not be possible. Many brands have adapted their formulas to help prevent crystal formation:

Royal Canin: S/O Index
Hill’s: S+OX Shield
Purina Pro Plan: St/Ox Safety

If your cat has struvite crystals and prevention isn’t enough, you may also consider supplements such as: