Bladder Stones and Crystals in Cats: Types, Signs and Treatment

By Tailwisp Editorial TeamUpdated October 20, 20264 min read

Few cat conditions are as painful or as urgent as urinary stones. Crystals and stones form when minerals in the urine come together, and they can irritate the bladder, cause bleeding and, in the worst case, block the urethra. Knowing the types and what to do can protect your cat.

Crystals versus stones

Crystals are microscopic and are found by examining urine. Many healthy cats have a few crystals, and they do not always cause problems. When crystals clump together or grow, they can form stones (uroliths), which range from grains of sand to pebbles several millimeters across.

Common types

Struvite. Struvite crystals and stones are common, especially in younger cats. They tend to form in alkaline urine and are often linked to diet and, sometimes, infection. Struvite stones can often be dissolved with a special diet.

Calcium oxalate. These have become more common over the past decades. They form in more acidic urine and are more common in older, indoor, overweight cats and certain breeds, such as Persians, Burmese and Himalayans. Calcium oxalate stones do not dissolve with diet, and usually need to be removed surgically.

Other types, such as urate and cystine stones, are rare.

Signs

• Straining or crying when peeing
• Frequent trips to the litter box with small amounts of urine
• Blood in the urine
• Peeing outside the litter box. See why is my cat peeing outside the litter box.
• Licking the genital area
• Lethargy and loss of appetite
• Vomiting, in severe cases

Emergency: blockage

Stones and crystal plugs can block the urethra, particularly in male cats, whose urethra is narrow. A blocked cat cannot pee, and toxins and potassium build up quickly. Without treatment it can be fatal within one to three days. Signs include repeated unproductive trips to the box, crying, hiding, vomiting, a painful belly and collapse. See signs of a urinary blockage in cats and go to an emergency vet immediately.

Diagnosis

Your vet may use:

• Urinalysis to look for crystals, blood and infection
• A urine culture
• X-rays, since most stones show up, or an ultrasound
• Blood tests, especially for calcium levels and kidney function
• Stone analysis after removal, which tells you the type and guides prevention

Because signs overlap with other bladder problems, tests are needed. See urinary tract infection in cats and feline idiopathic cystitis.

Treatment

Blocked cats need emergency care, including a catheter to relieve the blockage, fluids and hospital stay.

Struvite stones can often be dissolved with a prescription diet fed exclusively for several weeks, plus antibiotics if infection is present. Progress is checked with X-rays and urine tests.

Calcium oxalate stones are usually removed surgically, or sometimes by other procedures. Diet is then used to reduce the chance of new stones.

Pain relief and fluids are used as needed.

Prevention

Preventing recurrence is a lifelong project.

• Increase water intake. Dilute urine makes crystals less likely to form. Feed wet food and offer fountains and multiple bowls. See how to get a cat to drink more water and wet vs dry cat food.
• Feed an appropriate diet. Your vet may recommend a prescription urinary diet. Do not use one without advice, since the wrong diet for the stone type can make things worse.
• Maintain a healthy weight. See how to help an overweight cat lose weight.
• Reduce stress and keep litter boxes clean. See how often to clean a litter box.
• Do regular rechecks. Urine tests and, sometimes, X-rays every few months at first.
• Avoid unnecessary supplements. Some mineral and vitamin supplements can affect urine.

Breed and age risk

Some breeds are more prone to calcium oxalate stones, and middle-aged to older cats are most often affected. Overweight, indoor cats that drink little have the highest risk. See Persian and Burmese profiles for breed context.

Living with a stone-former

Cats that have had stones are likely to form them again, so make prevention part of daily life. Weigh your cat regularly, measure meals, and keep a note of how much your cat drinks and how often it uses the litter box. Report any change quickly, since early treatment of crystals can prevent a painful blockage or surgery.

When to see a vet

Go to a vet promptly for blood in urine, straining or frequent small pees, and immediately if your cat cannot pee. Use the US vet directory to find a clinic, and see cat vet visit costs to plan for surgery or hospitalization.

This article is general educational information, not veterinary advice. Every cat is different. If your cat is unwell, or you are unsure about a symptom, diet change or medication, contact your veterinarian.